User blog comment:DirgeOfCerberus111/Space Wolves Successors: Canon or Not?/@comment-4608429-20121105000130

There is also this:

" They were disbanded for the same reason there could be no further Successors to the Space Wolves—the existence of the Wolf within. The genetic code of the Space Wolves Astartes known as the Canis Helix was far too dangerous to be copied"