"In answer to the actual thread-title question ; Yes, there is an outside chance that they COULD !"

It seems to be a pretty slim outside chance though. The BBC site has a seat calculator and I put in 36.9% of the vote for the Lib Dems; 33.7% for the Conservatives; 25% for Labour and 4.3% for others. Incredibly enough on those figures it would still see Labour as the second biggest party on 204 seats with the Tories on 249 and Lib Dems some way back on 171.