He says a lot of things he wishes to come true. Won’t happen.

And Mexico will pay for it!

Courts will strike it down

This implies Harvard somehow makes a profit. I’m pretty sure Harvard’s accountants can show they have nothing to pay taxes on even with a large endowment, and especially if they are funding research formerly supported by the federal government. Also property taxes are not collected by the feds, so I’m also pretty sure they still won’t pay property taxes. They don’t really have shareholders to worry about. I think this is just Trump being clueless again.