I think the odds are that Romney will lose narrowly, but we will probably keep the House and possibly recapture the Senate.
The reason we are stuck with the chameleon is because enough Republicans know that the last non-Romney standing, Santorum, would lose in a crushing landslide defeat that would take down our House majority with it and ensure we have no chance of taking the Senate.
The outlook isn’t good, but sure, Romney has at least some chance depending on how events unfold. I’d say Hussein has a 66% chance at re-election at the moment against Willard. Were our nominee Rick “lets talk about why contraception is ‘not okay’” Santorum, Obama would have near a 100% chance to win.
You are wrong. If/when Romney loses, he will lose part of our margin in the House (and maybe the whole margin). Conversely even if Santorum lost, he would swing House and Senate seats to R.