Triple H has mentioned during recent NXT conference calls that WWE will have NXT specials on the WWE Network every four months or so. The next special will happen on December 11. Assuming WWE follows its four month schedule, that would have the next event in March 2015, right before WrestleMania 31.
There has been talk in WWE that the NXT roster may be brought to San Francisco for a live NXT Network special during WrestleMania 31 weekend. However, problems could be created from attempting to run an event like NXT Takeover with all of the other AXXESS events going on.