Dominant Party is a good way to put it.
In the meantime, the GOP will be dragged inexorably Leftwards in order to remain viable.
Don’t count on it. If the GOP attempts to become a completely centrist party, embracing abortion, debt, welfare, etc, their support will simply collapse underneath them.
I’d rather live in a openly majority-backed dictatorship than a banana republic.
Interesting analysis. And historically your comment that the "minority" party will inexorably be dragged leftwards is also correct as seen from the Swedish perspective. However, when the change eventually came, it came via a true conservative who got fed up with the timid party hierarchy and took over the party leadership in something of a coup.
His message eventually (and continuously) helped to unset the almost unbeatable social democrats. But it took more than 2 election cycles, and even then it took another few election cycles to safely post the conservatives at a level between 20 - 25%. (Coalition governments are very common not only in Sweden but most European countries with a proportional voting system.)
Note, however, that the change in Sweden took place during the red 70s, a coupleof years before Reagan and Thatcher transformed the international standing of conservatism.