It's based on the leaked Destiny calendar saying March for House of Wolves. As they just announced it will officially be Q2, and that's April-June, everyone's saying it's delayed. I don't necessarily agree, since the leaked image wasn't an official announcement. They may have pushed it back a long time ago, or it could be that was their projected timeline last summer. Who knows? But what we can say is that there's anywhere from 3-5 months before the next significant content update occurs.