There is no word on when Island Paradise or the third expansion may be coming, but University Life will be released sometime in March 2013. From EA's announcement:
The Sims 3 University Life will give players an opportunity to leave home and attend university, where they will enroll in classes, earn degrees and discover the crazy antics and hijinks that go hand-in-hand with the college lifestyle. From juice-keggers to new social groups, to protests in the quad and young love, there’s much more to university than time spent in the classroom. Sims will explore an all-new college town filled with new locations to visit such as the bowling alley and SimBurger and discover hidden talents through an array of extra-curricular activities, including spray painting murals, playing games of kicky bag in the quad and so much more!
It seems the partying will be a major focus of the expansion pack. The Limited Edition version of the expansion comes with a toga outfit, a masquerade mask, and a "Partaeus Maximus" statue. The trailer below also highlights the partying, which includes beer pong, keg stands, and streaking.