Let’s see, Obama can start an unconstitutional program but Trump can’t end it. Only if you have 5 or more Supreme Court Justices who can’t read.
The only way it’s a Constitutional program is if it is a valid exercise of prosecutorial discretion, which according to 8 U.S.C. 1252(g) is not reviewable by any court. So the decision to rescind it is entirely up to the President. Also, the memorandum setting up specifically said the program does not confer any substantive right on any participant.
So this case is a slam dunk loser, and the dreamers are wasting their money lining the pockets of some greedy lawyers.