Andy wrote above:
"If the Republican Party cannot defeat a geriatric Brooklyn socialist who dresses like an unmade bed and whose platform includes 90 percent income tax rates and nearly $20 trillion in new Federal spending - an amount exceeding our annual GDP - then they ought to disband."
This could in fact happen.
As unpredictable as Donald Trump's rise has been (running as a third party candidate, nominally Republican), the same can be said about Bernie (running as a socialist, nominally democrat).
If both of them win their respective nominations, things could go either way.
If Bernie goes on to win, it won't hurt the democrats at all, because an increasingly large number of them are openly socialistic or closet communists today.
But it's going to be tough on the Pubbies regardless of the winner.
If it's Bernie, as you said above -- if the Republicans don't have the electoral horsepower to win against a faux-communist, they're finished as a national political force (and I say that regardless of the fact that the majority of state governments are currently dominated by Republican majorities).
If Trump wins, the old-boy Pubbies are in just as much trouble. Even with their do-nothing majorities in Congress, they may be unable -- or, more likely, unwilling -- to work with a President Trump, largely out of spite.
A bleak future, down both forks of the road...