I think the part that is "delusional" is his thinking he cannot be taken down, and that his grip on these politicians is forever.

All humans and megalomaniacs can be taken down....i.e. Saddam Hussein, hiding in a literal rat hole in the ground but still proclaiming his supremacy as president.

And as noted in the 60 minutes segment, some GOP signees are already ignoring their pledge they signed years ago.

They've been appeasing Norquist--feeding a crocodile, hoping it will eat them last--but maybe they've realized they'll get eaten soon anyway. The 60 Minutes segment is a good start.