I was initially very sceptical if he would ever see the inside of a jail cell but given the sheer volume and severity of the numerous cases against him, I think it's almost certain he will spend the rest of his life in prison (based also on his age of course).
The concern here is what happens then? He's already gone a pretty long way to destroying anything left of American democracy and decency. But the forces he's unleashed aren't going away. I actually fear what comes after him. That's not to suggest for a second that he shouldn't be prosecuted, more that Trumpism as a insane hard right philosophy has set root in America. And the next person to pick up the mantle might be smarter and even more ruthless than him.