> And what are the repercussions if he does NOT achieve all these within the first 100 days?

He will claim that he did indeed achieve them despite all evidence to the contrary.

If you manage to corner him on the argument, he will blame you for the failure.

* edit. Not sure what the downvote is for. Trump has used both tactics outlined above. He was always against the Iraq war despite evidence to the contrary. When he was under the impression that he would lose the election he cast blame elsewhere (election rigging).