I voted for DT twice, but he’s 76 yo - 78 next election. I’m a boomer and can admire his energy but not close my eyes to reality. I don’t know who the Dem nominee but I bet s/he will be decades younger than DT.
That depends. One reason why the Dems are so desperate to have Trump be the GOP nominee is that they're confident they can beat him with Biden.
They're less confident throwing Biden against a different GOP candidate. And they're also not looking forward to an ugly primary battle against an incumbent president. Many Democrats still believe that Ted Kennedy mortally wounded Carter's '80 re-election campaign before Ronald Reagan delivered the death blow.