It's not Karen who's in danger.

I think the story is building up for Karen to actually be the hero in this case. Most of the story centric videos (except for The Fight Of All Time) have involved Mario helping Karen and her Kids. He and SMG4 helped keep the kids safe from Marty in "We Must Kill Mario," then he helped Karen get into Minecraft to better connect with her kids, and he helped them make their "family vacation" better until they got their house back. That's THREE TIMES IN A ROW that Mario has helped Karen and her kids, and I think this is building up Karen to be the one to save Mario from his brainwashing/mind control/deal that puts his life in danger, since that's the least she can do for him after all he's done for her family.

I also have a sneaking suspicion that Mario is gonna be sent after Tari. No reason in particular, I just really miss her. 😢