I can still imagine there might be some sort of wall or other wall-like border obstacle built on the US-Mexico border. What I can't imagine is Mexico paying for it like Trump wanted. No way in hell can Mexico afford such a project and not go bankrupt. Not to mention they have absolutely no interest in it.
Wait and see on that. You can bet that he will fill his promise that Mex will pay for it.
The fact that it seems totally illogical and impossible is part of why he'll be impelled to make it happen.