Actually, instead of ignoring the law, if we change the law it's a political win for republicans. Attorney General Sessions (who has the authority under the Controlled Substances Act) can say, "I have administrative authority to remove pot from schedule 1 of the controlled substances act, because it has been found to have medical benefits and a limited potential for abuse, so I'm removing it." That would be a huge step in the right direction from simply ignoring the law. I personally disapprove of marijuana, but I have mixed feelings about legalizing it. Even with my distaste for pot though, I would very much prefer changing the law to simply ignoring the law.
I hope President Trump will either enforce the law and articulate why that is good for our children, or change the law and argue why removing that drug from the banned list is good for America.
Conservatively: Having laws you don’t intend to enforce is deleterious to law abiding. So, either enforce or repeal.
Politically: Loser issue for Republicans. The pot issue can only bring pot heads off the couch to vote D (if enforced) or keep straight edge conservatives from voting R (if repealed). I don’t get the winning play here, politically. I’d just leave it alone for the first term. Do one of the two Conservative approaches in a second term, when Trump can handle any outcome.