Back to back National Emergencies? Not even Trump is that stupid. Not to say he won't try it again, but I think he's smart enough to allow for a cool down.
I don't follow your logic.
How many people thought he was "too smart" to try for a bumpstock ban?
Or a trade war with China?
Or a muslim visa ban?
And to declare an emergency over a non-emergency?
If the rules don't prevent him from doing something, he sees that as authority to do that thing. (And, in terms of executive authority, he's probably right.)
I can absolutely see him turn around and declare something closely related to the wall as a new emergency.