They're already working on a constitutional amendment to allow a third term[0] and right wing lawyers have suggested that there are legal strategies Trump could try employing to stay in power. That along with Trump himself "jokingly" saying that we won't need to vote again if he's elected does not inspire confidence.
0: https://ogles.house.gov/media/press-releases/rep-ogles-propo...
He isn't. Even absent any impact that catching covid may have had on his body, he's visibly obese. More detailed reports on his health are hard to come by thanks to (a) that being private, and (b) the extremely noisy people who either want to demonise or deify him, but it's not unreasonable to think he's got a 25% chance of old age catching up with him fatally by the end of this term.
But if the term limits get scrapped, I wouldn't be surprised to see a return of Bush or Obama as alternatives. Or Bill Clinton. Bill, George, and Donald were all born in 1946.
(1946 was also the same year the United Nations General Assembly and Security Council started meeting. Coincidence, or the secret world government? Coincidence, obviously).
That's optimistic.
We put a business executive in charge of the federal government. There's no such thing as term limits or checks-and-balances in the mind of a business executive, just taking a good horse out of the race and inefficiencies. On the first count, if Trump's still in relatively good health, I could absolutely see him making that case for scrapping the term limit on the Presidency.