I would argue that Jimmy has always been the semi-functional one. He had the focus and determination to finish a novel, owns a house, has been in a semi-serious relationship previously (with Becca, but still), was able to sustain friendly relationships in the old folks trailer park, and has for the most part been a decent partner to Gretchen. He obviously has his own issues and doesn't deal with problems well (clearly), but I remember him doing lots of little, loving things for her (the YouTube animal cruise, the murder crime spree and generally fighting really hard for her when he fucked up (and yes, he fucked up hugely). I haven't re-watched any of the seasons since they aired, but as far as I remember, the one time Jimmy needed Gretchen for real support when his father died, she freaked out and got him drunk.
This is my prediction for what happens and my hope for what happens. I would be very happy with that.
I thought it was perfect! Jimmy is a narcissistic snob who feels like he doesn't get the acclaim and recognition that he deserves. Now he gets to be part of some exclusive club so that he can look down on other people, and yes, hold court. And while I think he would be happy to hold court with anyone who would be willing to listen to him, beautiful women and other snobs is probably the best case scenario for him.
I don't like where Paul and Lindsay are going either and I really, really hope its a misdirection.