Chris is getting SSDI (or SSI) for life, or at least as long as the US government can afford paying it. He's been getting it for like 20 years now, she's long past anyone even bothering to check her status.
I'm a socially exceptional autist myself that's gone through the process over the last few years as a lolcow myself, I know how this works. I can guarantee that Chris will receive services to ensure she has health care, will be forced to maintain that health care, and will have a roof over her head. She'll have, or already has, a care manager specifically working with Chris.
I think Chris will change significantly for the better once Barb's toxic influence is finally out of his life. We see how Chris mellowed and became more accepting when Bob died, and Barb is/has done far more damage. One immediate change will be the end of spending recklessly on toys and stupid shit, whether Chris likes it or not. Chris does seem to understand the value of money outside of her splurging which Barb has always enabled, and seems against and ashamed of Barb's hoarding and generally awful ways. I also assume there's a whole mess of mental issues that we aren't aware of that Barb has at least perpetrated.