Plus, even if Prop 8 passes, it won't the end of the story.
There will be constitutional challenges. For example, it's far from established that you can change the California constitution significantly by a voter initiated proposition that side steps the legislature.
And then there's future votes, which is why it's ridiculous to change the constitution on a moving target social issue like this. Previously, the voters voted anti-gay by a significant margin. This time the anti-gay side will be defeated or will win by a small margin. Next time round or the time after that, as the bigoted old farts die off, the anti-gay side will lose.
In the meantime, the domestic partnership side of things stays in place and Obama has promised to give civil unions the full rights and benefits of straight marriage, which is the situation in places like England. I used to think that that was second class citizenship, etc. But the reality over there, as far as I can see, is that you wouldn't know the difference and, after a while, flipping over to gay marriage as such, if anyone is still bothered about that, will be a lot easier.
So there's no need to move. They can delay gay marriage, but they can't stop it.