If the Democrats embrace the old centrist "Blue Dog" model they'll have control for a long time. The Republicans screwed up redistricting everything, it turned more places a purple state. And purple can go blue faster than red. If they leave the freaky deaky blue states like California alone, and concentrate on flipping purples, they'll have it.
Vance is done. They're not cleaning up this mess in 2 years, and to the average American, Vance is just an extension of Trump no matter what he says. Also Vance isn't Trump's friend, they are simply a pair of people brought together over need of what the other had. Trump will show lackluster support for Vance at the end, and it will be a wrap for JD. Trump is probably waiting to play "I told you so" with a failing Republican party in 2028.