The news came straight from a candid question at the creator's tables, Misfits fans were warned not to look forward to next volume, because she has no idea if/when it'll ever come out. Of course, Deb at Manga.About.com got her sleuthing hat on. Talking with Raina Telgemeier and husband/collaborator Dave Roman, they had this to say on the matter...
Wolverine: Prodigal Son series is also on the chopping block, though I didn't actually like that one. Misfits seemed fairly successful, so one can only speculate on what else must be going on behind the curtain.
Wow! News travels fast! @goraina and I super disappointed since it was written as a 2-part story and it will be unfair to readers.We only found out last week. We still don't have a lot of the details beyond it being a cost of licensing vs. profits issue. :/ I only saw about 20 pages of Book 2 pencils a few months back so I assumed Anzu was far along, but still deep into it. Those are the emotions that I keep going through regarding Misfits. Confusion then disappointment. Most successful non-success.
The most likely culprit is, of course, licensing issues with the Marvel IPs. This seems all the more likely if we just set our way back machine to remember how Disney bought Marvel late summer. Anyways, check out Deb's blog for her entire findings.