I'd say this is a very real possibility, especially if his status within his own party would start to look a little less than totally secure. Would he even be certain of being re-elected in Sheffield Hallam?
A poll was commissioned mid-October 2010 by Conservative donor Michael Ashcroft asking just that, which shown in Sheffield Hallam voters would split:
33% Liberal (-20.4%)31% Labour (+15.0%)28% Conservative (+4.5%)Whether all that's happened since then (not least the tuition fees tripling) changes that is something for future polling, but his re-election is clearly not certain. Interesting that in the days when there were no Liberal presence, Hallam was consistently Tory, so if Labour were to oust him it'd be like 1983 in reverse, with them slipping through a split-Right vote (unless boundary changes makes that comparison shaky).