Even if this amendment passed the Senate, passed the House, and was approved in all 50 states, it wouldn't matter. It would be held up in courts and liberal judges everywhere would declare this constitutional amendment UNconstitutional, and that would be that. I doubt that very many gays, activists or otherwise, are exactly quaking in their boots. They know they have the MSM, the courts, public education, Dems and RINOs on their side. What do they have to fear??
Constitutional amendments cannot be held to be unconstitutional. Amendments are not mere tacked on sticky notes - they are, by definition, part of the Constitution. You might get civil disobedience from certain officials of course, but only at the lower levels, and they would be corrected.