I think that the SS nerf is actually going to cause real issues in 25 mans, as it leaves 0 room for error when someone is going into a SS rotation. So if anything happens that makes you move, etc, you're going to have wasted the cast. Disc will still be strong, of course, because it's Disc and bubbles and Barrier, but it's a source of aggravation.
I have a guy in my guild who does nothing but trash talk Holy and went so far as to change his offspec to Shadow to avoid having to play Holy ever (even on Tortos). So I think there will be some people who refuse to try Holy regardless of the situation (
he literally told me that my spec doesn't exist ).
Then again, he says bubble spam in Wrath was the best fun ever. lol