I don't think it makes any sense to put ideology aside, that is half the equation, the other half being electability. With every poll that emerges showing Obama vulnerable, the electability quotient becomes less important relative to ideology. I submit that Gingrich's ideology, while not perfect, is far more reliable than Romney's.
I agree with you that Herman Cain will probably fade but we have to wait for the evidence of that, meanwhile, it is merely a subjective hunch that you and I share. If he does fade, Gingrich emerges as the only tenable alternative to the Rino.
"... The staying power, consistent support, field organization, discipline, focus, and endorsements" which you cite as attributes of Romney can be seen as weaknesses. Staying power is not of much use after five years with no forward progress. Rather than strength, it and the other attributes betray a limiting weakness. Rather than Romney being consistent it is the three quarters of the Republican Party in stubborn opposition to him which is consistent.
I'm afraid we're going to have to let the drama play out and, whether we like it or not, Karl Rove, as you point out, will play his part.
I like Gingrich. A lot.