... and maybe Dear John would be alive.
Yes. If John had lived, I feel sure that by now him and Paul would have drifted together at some point. If not to reform the Beatles (George wasn't so keen on that), then at least maybe a Lennon/McCartney project, with the albums entitled precisely that. There's a real precedent for it in The Ballad Of John And Yoko!
They'd be making an album like "Venus & Mars" in the mid-70s that's for sure.
... I can't imagine Paul contributing to a Walls and Bridges type album (maybe)
I've played this game lots of times and it always ends in the same way: I lose 'cos the guys have not carry on...
I sure hope they wouldn't have gone disco! Lol!!