I think it would mostly be generic Republican VS generic Democrat. I'll keep in mind that in order for Biden to beat Hillary, he'd have to show more talent than we currently give him credit for.
Bush would probably win, because it's unusual for the party in the White House to win a third term, and Biden's not a particularly strong opponent. This is my guess for the usual map.
Bush/ Haley- 286 Electoral Votes
Biden/ Klobuchar- 252 Electoral Votes
If the environment is good for Biden, he could win.
Biden/ Becerra- 285 Electoral Votes
Bush/ Ayotte- 253 Electoral Votes
The environment could also end up being better for Bush.
Bush/ Martinez- 317 Electoral Votes
Biden/ Gilibrand- 221 Electoral Votes
I just went with Veeps who seem plausible. It's unlikely to make a significant difference in the outcome.
