We have our Reagan Coalition...kinda
But, we have representatives still in the race that represent each faction:
Huckabee: Social Conservatives
Romney (and some Ron Paul): Fiscal Conservatives
McCain: Defense Conservatives
The elements are there, but not together. Give Huckabee the nomination and it will spurn fiscal and defense. Send up Romney, and social (and some defense) will go away). McCain tends to spurn almost everyone, except blue-blooders.
Too bad we can't morph them together.