I don't know if Luka is coming back or not, but I do know this:
The Lakers organization doesn't leak shit. Any reports you see from guys like Shams, Windy, Haynes, etc. (or random Twitter doctors) are completely uninformed and pure speculation. They don't have inside sources.
When LeBron signed with the Lakers back in 2018 it came out of nowhere (even Woj didn't report it). The Luka-AD trade was also completely done in the shadows with no leaks to any reporters/insiders. And too many other examples to list.
It is entirely possible that Luka won't be back for the playoffs, sure. Personally I don't believe he is coming back this round (just being realistic and I think the Lakers will be cautious with him). But it is also just as possible that he has been ramping up secretly and could make his return soon.
That is all. Lakers in 5.
EDIT: Btw they have not ruled out Luka for all of Round 2 despite knowing the full Round 2 schedule (and knowing that it ends in 2 weeks on May 18). If they knew Luka was still 2+ weeks away then why not just announce right now that he is out for all of Round 2?