In this context, I'm referring specifically to the Humboldt Park and Westchester branches, since the Blue Line replaced the Logan Square and Garfield Park branches, while the Douglas branch is now the Pink Line.

Westchester branch

In the case of the Westchester branch, things are pretty straightforward. What killed that branch was, well, the Great Depression. Between the Depression and World War II, a lot of the development that might've sprung up around the line and generated the ridership to convince the CTA to keep the line open never materialized until it was too late. I think with this"what if", things are pretty straightforward: the Westchester branch would be incorporated into the Blue Line. So the Blue Line would be "22nd & Mannheim to O'Hare via downtown".

Humboldt Park branch

With the Humboldt Park branch, things are a bit different. This branch might've developed the ridership needed to survive if it had been extended across the Milwaukee District North/West Lines and continued all the way to Harlem Avenue as originally intended. In addition, it's worth noting that before the CTA was formed, the Milwaukee-Dearborn Subway wasn't going to replace the elevated tracks along Paulina at all. Rather, it would supplement the old tracks, not unlike how the State Street Subway supplements the North Side Main Line between Armitage and the Loop.

So let's say that the Humboldt Park branch was built out to Elmwood Park, and the CTA didn't close the elevated tracks south of Damen. The Logan Square branch still gets rerouted into the subway, and in 1958 is connected to the Congress Line to form the initial part of what is now the Blue Line, and that line gets its extensions to Jefferson Park in 1970, to Rosemont in 1983, and O'Hare in 1984. For the Humboldt Park branch meanwhile, well, I think it's safe to say that once the Garfield Park elevated was replaced with the Congress Line, new track connections would be built at Lake Street Transfer to allow Humboldt Park trains to use the Lake Street Elevated to access the Loop, as was the case for Douglas trains during the Congress's construction and for Pink Line trains today.

This would probably have a knock-on effect with other routes down the line.

• I think the Douglas Line would still be connected to the Congress Line, resulting in the Blue Line's 1958-2008 O'Hare-Congress/Douglas service pattern still being formed.
• Humboldt Park trains would run with Lake Street trains into the Loop. Come 1969 when the Dan Ryan Line opened, the West-South Line would be known effectively as the Lake/Humboldt Park-Dan Ryan Line upon the through-routing of Lake trains to the Dan Ryan. Similar to how things were with the Blue and Red Lines before 1993, the skip-stop patterns would probably result in 'A' trains being all routed via the Lake Street Elevated while 'B' trains would be routed via Humboldt Park.
• That in turn would have a knock-on effect with the swapping of the South Side lines in 1993 that was done to balance out ridership levels and free up capacity for the Orange Line. Because of the South Side Elevated splitting into the Englewood and Jackson Park branches, I think each branch would've been paired to just one of the West Side elevated branches and each given its own color identity (Lake-Englewood being the Green Line, while Humboldt Park-Jackson Park forms what I'll call the 'Teal Line'; they not only differ in their outer branches).
• I wonder whether or not the CTA would've still separated the Douglas Branch from the Blue Line to form the Pink Line as is in 2006. My guess is that they probably would in order to add additional capacity on Lake Street and the Inner Loop.
• The differing ridership levels would certainly impact the design of the CTA's various orders for new trains during these years, particularly with the 2200 series and beyond. More cars would probably get built for what we know as the 2200, 2400, 2600, and 3200 series (which would all have slightly different names).

I can't help but feel like the whole situation with Lucy getting caught by the Legion, and Cooper having to rescue her, could've all been avoided if Cooper had taken five minutes to properly explain to Lucy why she shouldn't help the wounded slaves at the hospital.

Let's say everything is the same up until Lucy and the Ghoul walk by the abandoned hospital and hear the cries for help. Lucy insists on going in to help, and the Ghoul reluctantly follows her in. They enter the hospital and find the slaves in the kitchen. But once he recognizes the two wounded people as Legion slaves, the Ghoul decides to be more upfront with Lucy, because he cares about her (even if he doesn’t want to admit it), he needs her to be intact so he can use her as a bargaining chip with her dad (which she doesn't know), and he knows how much danger a woman like her is in when in Legion territory, as she's a Vault dweller with intact reproductive organs.

So the conversation goes like this:

>The Ghoul: “Tunics. [to the woman] You awful far west, ain’t you?”
Lucy: “Ignore him. I got one stimpak left, okay?”
The Ghoul: “That would be a profound misallocation of resources. Folks in them outfits don’t deserve savin’.”
Lucy: “What are you talking about? These people are hurt. Everyone deserves savin'.”
The Ghoul: “Not these people, vaultie. These are members of Caesar's Legion. Helping them would be the stupidest thing you can do."
Lucy: "And why's that?"
The Ghoul: "They’re assholes trying to bring Ancient Rome to the Wasteland. If you’re not with them, they'll beat you and enslave you or string you to a cross. And if you're a woman, well, you're only useful to them for making more babies.”

If I had to take a guess, Lucy would probably still insist on helping the slaves in the same way she took time to free the captured ghouls in the Super Duper Mart. So she'd probably still give her last stimpak to the female slave, and maybe ask the slave to bring her to her camp so she can find medical supplies and make an attempt to free them. And in her attempt to liberate the slaves without resorting to violence, she still gets captured and has to be rescued.

Though there's also the chance that she makes a different decision, and thus she and Cooper are able to avoid the Legion entirely. Or they both get captured and have to work together to escape.

Considering how season 2 ended, and us having to wait for season 3 to start filming so we can get set leaks, it's hard to say whether we'll see Lucy adapt a new outfit or she'll stick to her Vault 33 jumpsuit.

And she could go either way at this point.

On the one hand, Lucy could take on a new outfit to show she's shed her identity as a Vault dweller. She might do so because her views of Vault 33 are tainted by everything she's learned about her dad. And it might be a smart idea seeing as wearing a Vault jumpsuit could get her in trouble down the line.

But on the other hand, maybe she'll want to keep possession of her suit. After all, the last we saw of it was when she was looking herself in the mirror after changing into the yellow dress, so I think she intended to change back to the suit after her last dinner with Hank. And even with the last scene being her wearing the yellow dress while with Maximus inside the Lucky 38 penthouse, she'll likely still want to scour the management vault for information about her dad's work for the Enclave.

https://preview.redd.it/hg5z5nzlks2h1.png?width=1920&format=png&auto=webp&s=8a1f0e5a2ddd869a0ffe425560284335e178105a

And keeping Lucy in the Vault suit might also keep her thematically tied to Cooper. Cooper's cowboy costume inspired the color scheme of the Vault suits, after all, and he still wears that costume all these years later under his duster. With the duster symbolically being a sort of armor he wears to mask his pain. I could see Lucy keeping the Vault 33 jumpsuit but accessorizing it with a similar article of clothing on top of it, which could come in handy if/when she ever goes off in pursuit of Cooper (as we know she'll want answers regarding what her dad was up to, regarding the people he worked for, House needs someone to be his foot soldier, and she likely wants closure regarding Cooper coming back to save her after having betrayed her to her dad). Lucy wearing such a getup when confronting the Enclave might even be appropriate since Vault dwellers have always been their biggest thorns in their side.

Plus I'm not sure if Lucy wants to wear any sort of NCR apparel. I think after she made that "matching jackets" remark in 2x04 regarding the soldiers who nursed her back to health, she might balk at the idea of taking any of their clothing (even if that's a bit hypocritical of her, considering that Vault jumpsuits are a different kind of "matching jacket").