This statement was made in a post on shadowpriest.com and picked up by Wow Insider last night.
Koraa also hinted at a broader review of the shadow tree but remained cautious about the extent of changes. The statement in full:
We'll be increasing Mind Flay's coefficient (base) by roughly 30% to start, and allow Mind Flay to crit. We may also do some tuneups to the Shadow tree as well, but as other players have mentioned the tree is really not the problem, just the base spells not scaling.
Hopefully we can get the new Mind Flay in the next build, but allowing it to crit involves rebuilding the spell completely, which may take some time.
The buff to mind flay's coefficient is a good starting point. A 30% increase will take it from 57% to 74%. That's still far short of other three-second cast spells, but it's a move in the right direction.
The crit component is very interesting and it will be fun to see how it plays out in testing. Crit isn't something we've worried about before. Even with a new talent to increase our crit bonus, it wasn't going to be something we stacked in Northrend. But if every tick of mind flay has the potential to crit, a la arcane missiles, the value of crit jumps massively.
[Edit: thanks MD!]
I think it's great that someone from Blizzard is finally out there talking about shadow priests. While the development of other classes has been an ongoing process with two-way dialogue and discussion conducted on the forums and in the blogging community, the silence on priests has been conspicuous. I hope this is the start of a new and more open approach to our class's future.