I think he would take $3 billion and reopen. I suspect that his problem will be the GOP congress which has no spine to speak of, never has. They will eventually start to murmurer and eventually do something like, we will do a CR for a few weeks so we can talk about funding for the wall. And of course the Democrats will not budge in that time frame. Trump will not go along with this GOP cowardice and they will eventually with Democrat votes pass this type of funding.
Trump will veto this bill and then the GOP will vote to override the veto and reopen the government. Trump will then pound the GOP traitors and the Democrats for this in the 2020 campaign and he will pick one or two GOP lackeys out and go after them in the primaries.
The wall should have been funded and mostly built by now. We had both houses and the presidency for two years and should have rammed it through the way the RATs rammed Obamacare through when they were in control.
That is certainly a possible scenario; however, you are more of an optimist than I about the next phase.
IMO, after such a veto it seems possible enough shaky RINOS in the Senate gifted with all manner of inducements would thereupon find it very easy to complete the impeachment process and throw Trump out of office.
I could be wrong though, I also thought that given what happened in plain view during their first 4 years there was no way in hell either Clinton or Obama would capture a second term.
He'd better not. The $5.7 billion he's asking for is only 1/10th of 1% of annual FedGov expenditures, as it is.
We need $21 billion to complete the whole project.