The LibDems have a particular vested interest in prolonging the Coalition – it’s the only way to get to the refererndum on AV (and with it, the only chance to maintain their current status in political terms).
As has been said above, a minority Tory government won’t last, so the Conservatives have no option but to put up with the arrangement too. However, from a PR perspective, they haven’t done badly out of it (mainly because everyone who hates them still hates them, whereas the same people like d the plucky LibDems until they got into bed with the nasty party).
So, they will do their best to patch things up post Christmas, and rumble on. I do wonder if the pace of change and policy announcements will slow, or if the Osborne and Cameron will continue to push their agenda so fast no-one will know what has hit them.