It is impractical, because there are not as many votes in the West as there are in the South.
You can believe all you want in the gays taking over Utah, but it won't happen, not ever.
The Gay and Lesbian population never exceeds 10% in any population. Presumably, they could all move to some underpopulated state and take it over, but this is even less likely than the Libertarians taking over New Hampshire, as some Libertarians have suggested. That won't happen, either.
Most people are just not so deeply into politics that they let it dominate their lves and al the decisions they make to live their lives.
Again, this is a deeply weird idea.
The Democrats and Republicans have never entirely swapped membership before. All that happened is that Southern bigots left the Democratic Party, because they did nt want to share with newly franchised Black voters. First they switched to Wallace, and then when Wallace was crippled by a would-be assassin, they switched to the Republican Party, at first only in presidential elections. The rest of the country did not switch.