If it happens, it has to be either after nov 5 , but mainly after inauguration day, because, otherwise, Trump will only serve last few weeks as his second term and be ineligible for 2025

I think he can serve 10 years. A VP can become president and then be elected 2 more times as long as the total does not exceed 10 years.

This would likely require a ruling by SCOTUS.

However, if we flipped back to original constitution prior to 1871, there would be no question.

A lot will be happening in the next few months.