Smart Republicans.... there are a few.

[Thumpalumpacus]

It seems to me that the Wall Street Republicans have a couple of options if the GOP breaks apart: they could go Libertarian (not a bad fit, really, since it doesn't seem that they are on board with the social conservative agenda except to secure needed votes) or they could be absorbed into the Democratic party, at least so long as the party resists being pulled leftward by the progressives.

I don't think they'll defect to the Democrats. After the Bern, business-types will likely be gunshy of allying with a party that cae pretty close to nominating a social democrat as its standard-bearer. I see the Libertarian scenario as much more likely given the resonance between small government and unregulated markets.

But where does that leave the social conservatives and Tea Party people?

I think they'll continue their, ahem, unholy alliance. Though the Tea Partiers are nominally small-government, they seem to favor abortion restrictions, which might be the thin reed by which each faction can justify allying with the other. I think these two factions will continue a rump Republican Party, but it's entirely possible they too could fly apart, though over which issue is not clear to me.

Are they what the GOP effectively becomes? If so, they will cease to be a force in Presidential elections, but they may continue to wield disproportionate influence in certain state legislatures and in the federal House and Senate seats representing such states. Somehow, I find this even more disturbing.

Indeed -- local elections have much more bearing on real-life issues we face than do Federal elections, a fact especially noticeable when you live in a conservative state, as I do.