Gen V and the Current Plot
Given what has been said in interviews, I'm finding it very probable Gen V cast is in the next 2 episodes since it's been said Marie at least helps in the final battle.
As someone who actually kinda liked Gen V (even season 2 to an extent), I don't like this. We have enough trouble rn finishing the show we are currently watching without including tie ins to other spinoffs (which we are already doing too much of with the VR stuff), so I worry it's either not gonna mean anything or take too much away from the current plot.
The OTHER problem is that you hyped Marie up to be something too big to pay off to fans of Gen V by doing this.
If she kills Homelander now it robs the main cast of their main motivation for 5 seasons, if she doesn't kill Homelander her own buildup in Gen V largely meant nothing. There is no winning in this scenario you are going to piss someone off.
TLDR: Introducing important characters from your spinoff show in the PENULTIMATE EPISODE AND SERIES FINALE is a terrible idea and if they wanted Gen V rep in this show so badly it should've started at the premiere of season 5.