As part of the AMA with ArenaNet's Mike O'Brien, it was revealed that the Guild Wars 2 Living Story should be making a return in time for the July update. In addition, the team will be focusing on the development of an expansion without sacrificing regular, current game updates as well.
We'll all miss Colin. And yes, Living World should come back around the time of the July quarterly update. We took it down at the beginning of 2015 to focus on HoT, and now we're rebuilding. My goal now is sustainability: we shouldn't ever have to sacrifice Live to ship an expansion.
Read more on the Guild Wars 2 Reddit.