Fiery issue? So what. No wall = Democrat President. He’s left with three choices: 1) shut down ALL immigration, NO exceptions (courts will overrule); 2) let everybody and anybody in (CA and NM only); or 3) resign in disgust and a big FU to what’s left of the geographical entity (least likely).
He has another chance at a shut down next October, if I recall correctly.
If for some reason (seems extremely unlikely to me) that his emergency declaration is overridden by super majorities in cogress, then he has no legs to stand on until the election where he can take it to the people. BUT, if he loses it in the courts, he still has the shut-down angle to use against congress to get the funding from them.