If the 15th of Feb rolls around and no deal is reached where he gets a border wall, what then? Trump declares a state of emergency, then what? Seems obvious, the Dems find a federal judge somewhere that puts a national restraining order on it. Ah, but what then? And on what grounds? Maybe Trump bypasses the Circuit Court (probably the 9th) and asks the DC Court of Appeals or the SCOTUS to rule on the restraining order, what then? I don't know about the makeup of the DC Court, but I do think there ought to be some limits on what a federal district judge can do outside of his jurisdiction, and that would be a good thing to get resolved. I'm guessing the DC Court or the current SCOTUS will rule in his favor, especially if RBG is unable to participate by then.
JMO, and I'm no legal expert, but I wouldn't be surprised if the higher Courts lift the restraining order, at least for the entire nation. Maybe the Court would decide that the federal judge can issue a restraining order for his district, but the person has no authority to do so for the whole country. At least not without sufficient grounds, which I doubt would exist. And IMHO Trump gets his wall.
That's the way I see this thing going, Congress doesn't have the balls to do their jobs anymore, obviously our best interests are secondary to their own. Could the higher Courts side with the lower court judge? Yeah, but that's too much power in the hands on one unelected individual if you ask me. And the Dems have to know, that whenever a future President is a Dem, the GOP will be doing the same damn thing to him/her. But that would be down the road, and nobody gives a damn about the future anymore.