It would never go into effect. The president can't make law with an EO. Clinton tried it and the courts said no. It would be stopped by the courts before it ever went into effect. Congress could also starve funding for enforcement.
But if he tried it and the courts and congress both fail in their responsibility to uphold the constitution, then there could be problems. I'm guessing states would be even more emboldened to stand up against the over reach of federal power.
But if he tried it and the courts and congress both fail in their responsibility to uphold the constitution, then there could be problems. I'm guessing states would be even more emboldened to stand up against the over reach of federal power.