I doubt that. I'll answer your question, but I doubt your motivation.
Let's leave aside the ridiculous, like actually shooting someone on Fifth Avenue; and the already happening, like throwing Ukraine under the bus.
How do you know he's "throwing Ukraine under the bus"? What actual evidence do you have that he's doing that? Is it just remotely possible that Trump is using common posturing negotiating tactics to allow Putin to save face while ensuring that Ukraine keeps most/all of its territory and remains independent in for the long term? Has it occurred to any of you that this is what he's doing?
And ignore the possibility of his turning liberal, or gay, or atheist or something.
This is silliness. Obviously, if Trump turned liberal, he would lose conservative support and would lose at least some centrist support. Many Trump supporters would not care if he declared he was gay or atheist as long as he continued to support the main policies on which he ran.
What could he do that you would consider stepping over the line? Openly allying with Russia?
It would depend on the issue/circumstances. During the war on terrorism, the U.S. and Russia sometimes had a common enemy. If Trump forces Ukraine into a peace deal that leads to Russian control of Ukraine, I would loudly condemn him for the betrayal. Does this mean I would start opposing him on every issue? No, of course not. But I would certainly say that his betrayal of Ukraine was disgraceful--again, if he in fact does betray Ukraine.
Invading another country to seize territory?
Well, again, it would depend on the circumstances. Generally speaking, I would oppose such an action, but I can envision a few scenarios where such an intervention would be justified, or at least understandable.
Declaring himself President for life?
Yes, obviously, that would be a deal breaker. I would support his impeachment and removal from office if he attempted such a move.
I promise I will read all responses, even if you are on the list that shall not be named. Maybe even take you off of it.
Anti-Trumpers: Let's give them a while before piling on, okay?
Right, let's let the knuckle-dragging Neanderthals have their say before we deign to grace them with our infallible woke enlightenment and brilliance. Sheesh, listen to yourself.
You folks might, just might, want to keep in mind that Kamala Harris lost the popular vote by over 2 million votes, lost every swing state, and lost the Senate. You might also want to keep in mind that 27 out of our 50 states have elected Republican governors. Apparently there are tens of millions of Neanderthals voting in America.