If he'd announced it after the NATO Summit, when I'd expected him to say he was out, the Republicans might have picked someone other than Senator Vance as the VP. They're locked in and the Democrats get to choose a counter ticket.
The Democrats can pick anyone 35 or older who's natural born and has lived in the country for at least 14 years as the ticket. They can elevate the VP with President Biden working in the background to set things up well for her or to put up some obstacles for the Republicans if they win the election, and pick the candidate who would round out the ticket by filling in her low points and shaving off any sharp pieces.
It's not over. It's barely begun.