Can a Senate "trial" be legitimate if there are no witnesses?

[CaptYossarian]

4. He won't be convicted and there won't be a 25th Amendment invoked no matter what he does.

I thought about this while speculating about who Pence's Vice President might be.

It won't be a senator because the numbers are too close for comfort and it won't be an active House member because the GOP is at a deficit. It would have to be a "retired" party member. Bob Corker and Jeb Bush wouldn't fit the current nuttiness, which would allow former Trump ally Chris Christie to step in. He seems like a moderate (in comparison with today's cast of characters) and the base trusts him in spite of that. Another option could be why Mark Meadows might not finish his term in Congress. Christie has more national name recognition for the re-election though.

As for the 25th not being invoked, the cabinet members at this point must feel that Trump's insanity has become normalized to them. And what happens to the ones voting in favor of removing Trump if they aren't successful? Trump is dangerous, has no conscience or guilt, and admires world leaders who imprison or murder their rivals. That's also the dilemma faced by the Senate Republicans.