You are completely discounting Rubio. He's got more mojo than Kasich, and if the GOPe doesn't side with Trump, they'll go with him.
You're mirroring the same argument that you are trying to pull against Cruz and Trump. Kasich isn't electable because there's not enough people out there of the ilk you describe to vote for him. If Hillary gets the nomination, she will beat him in the race to the 'common sense' middle.
Let's also not forget Kasich's tendency wander tino the weeds sounding as preachy, righteous, and religiousy as any hard social conservative theocrat. He is also not going to beat Hillary in that department either. A philosophical wander-a-round isn't going to get it done. Jeb has already tried that and lost.
If the GOPe wants a candidate, Rubio is their best bet. And a hard conservative like me is much more willing to vote for him than a Kasich.