Of course it wouldn't succeed. The Supreme Court has ruled a number of times that monuments are legal, and large monuments are legal. They've also addressed expansions- in a case in the 1970s called US vs California which dealt with the expansion of then- Channel Islands national monument in 1949.  the court ruled that, even though a 3 mile band of water stretching from the coast of CA belonged to the state, the monument expanding into state waters was valid, as the US retained a stake in the waters. Expansions are part of the presidents discretion. this includes how much land and water to add. Most of FDRs uses of the Act were expansions to existing monuments. More recent presidents dont expand existing monuments as much, Obama has only expanded a monument 3 times. So any anti-monument challenge is going to fail, as the states dont have standing to challenge, and monuments are the presidents call, and his alone. Courts aren't going to overturn them.