In case you didn't know, they absolutely could end it with something like this. Just look at another one of the director's pieces, "Heaven's Lost Property". Same number of episodes, horrible, horrible ending. I want to stab someone it was so bad. They apparently turned the third season into a movie that isn't English dubbed till next year, but I've heard that ending is only marginally better.
Heaven's lost property didn't cliffhanger end lol. The new movie pretty much botched the manga plot line because they had to skip something like 2.5 VOLUMES worth of material :(
The animation studio doesn't have anything to do with the delay in a season 3 for Haganai. As I said before, the light novel does not have enough material right now to support a season 3 because the end of season 2 caught up to the light novels. The novels release painfully slow, so that is what is holding things up.