To be fair - it's really only the extreme evangelical/tea party factions that are permanently frozen out.
They will control the party via mass-denial until their 2016 thrashing, after which the republicans will rethink themselves into more of the modern libertarian party they are supposed to be.
That's why this last election was so bitter - a generation of very ideological, very determined, very devisive people knew damn will this was their last chance to go for gold.
The republican regenesis, and the wellbeing of the world in general, will be helped along considerably by the dwindling supply of people who were alive during Jim Crow. The young have much more inclusive attitudes to race, religion and orientation...
EDIT: @joseph b - that's my point. They SHOULD be able to court several minority elements but they CAN'T until the old guard is either dead or humiliated.