I think he wants to have a sort of capstone signature achievement. He has been wanting this for a long time. One of the best things his tax bills have done, for instance, is vastly increase the standard deduction. This effectively serves to cut the income tax on the vast majority of people.

I can't help but assume it's very unlikely that it happens though. But if he could even cut it in half, or nullify it for anyone below like 100k income (200k MFJ), that would still be a great step in the right direction. If it happens, I think something like that is the most likely form it takes.

Edit: And while I would love federal income tax to go away, the most evil tax anyone pays is property tax on their houses. If I could choose, I would get rid of that. But I realize that is a local and state tax, so orange man does not have much of a say in it.