Acting as a martyr he is gaining even more consensus. This can backfire... like what happened with, say, Berlusconi who got re-elected multiple times despite being prosecuted.
No it won't backfire. He'll act like a martyr no matter what happens or doesn't happen.
The only difference is whether he's held accountable for his crimes and pretends to be a martyr or not held accountable and still pretends to be a martyr.
As for the cult believing him, same deal. Following the leader blindly is what cults do.
True, I imagine he'd find something else to complain about. Although I also think that he had quietly slipped away (and not horde secret documents), people won't feel so compelled about prosecuting him.
He has all the support he's ever going to get. His supporters are probably going to go ballistic when he's convicted but they go ballistic most of the time anyway. He's not swaying on the fence voters.
He's actually repelling voters while at the same time splitting the Republican vote. He is actually the left secret weapon against the right, let Trump do as much damage as possible to the Republicans, and then come on in the campaign time, point out but he is basically trying to start a dictatorship.