I'm not so sure about that. They may have thought Romney had a better chance to win in 2012 than Gingrich or Santorum or Cain or Bachmann would have had, but I don't remember anybody saying that Romney was a sure thing. It's true that some of Romney's own circle were overconfident after that first debate, but nobody was that certain that he would win this early in the campaign cycle.
Similarly, somebody might have said that McCain would make a better candidate than Huckabee or Paul or Duncan Hunter. That's already a bit of stretch, though. Plenty of these Establishment Republicans (and conservatives as well, though nobody wants to talk about that now) preferred Romney to McCain in 2008. McCain was less of an Establishment favorite than you might think. He just managed to win more primaries.
Nobody, nobody, nobody, nobody, nobody said that Bob Dole was a sure thing in 1996. Look who he was running against though: Forbes, Buchanan, Dornan, Gramm, Keyes, Specter, Alexander, Lugar, etc. Are you really sure that any of them would have been that much better than Dole? Sometimes -- most of the time -- the ideal candidate just isn't out there.
You might be right