The only way Romney could win is if pretty much every poll had large sampling errors (which is what desperate Republicans are trying to argue). Sure it's possible....but Gary Johnson becoming President is also possible.
Johnson becoming President looks to more possible than Romney winning this time. He's only 59, so future Presidential runs are quite possible for Gary. If the national GOP veers libertarian to get out of its current presidential problems, he's got a shot at getting the GOP nomination in 2020 or 2024. I think the GOP is likely going to bet on a social conservative in 2016. (Not that Romney hasn't taken conservative positions on social issues, but they never have been a priority for him.)