They don't have to fight 50 fights. All they have to do is travel to the nearest same-sex-marriage state, get "married," and return home. Either all gay activists in states not recognizing gay marriage would do this, or what is more likely, enough would do it, that all the non-gay-marriage states would eventually simply bend over and take it.
Any State that simply bends over and takes it, deserves it. Anyone without the gumption to fight deserves it.
The Constitution places the right to define marriage on the States, if the simply bend over and take it, the failed to uphold their duties as American citizens, and the other side won.
The Constitution worked either way.