I'm always amused by political ponderings like this, because there is always the unspoken assumption that states are red or blue, and people just assume the political views of the state they live in. In other words, Texans are "red" because Texas is a red state, and Californians are blue because they live in a blue state.
I think the cause and effect here is backwards. Red states are red, and blue states are blue, because of the people who live there, not the other way around. Blue voters moving from blue states to red states probably won't become red voters, they will make the red state more blue. If the entire population of San Francisco moved to, say, North Dakota, it wouldn't become a more populated red state, it would become a blue state.
The problem is that you are trying to identify a fixed democraphic pattern in a fluid demographic. Red states are red only so long as a lot of red voters live there, if the demographic changes, you can't very well expect the election results to stay the same.