Does anyone believe this is permanent?
I think the more appropriate question is "How long do you expect this to last?"
I think the individuals who would like it resolved in the same timeframe as Knightfall or the Death of Superman are going to be disappointed. I discount that as being very likely, as, well, it's been done, and not too long ago. I doubt anyone would be interested in repeating that pattern. I do think it would be desirable for creators or sensible for the higher-ups.
Realistically? I think all other possibilities are fair game, including the possibility that DC has absolutely no plans to bring Bruce back. I don't think DC feels particularly bound to have Bruce Wayne back in the cowl by the time Batman III hits theaters, but I also think they may do it anyway. I think this entire event may have been inspired by someone reading Brubaker's Captain America, and realizing that, hey, this sort of thing
can be done. I think that the current climate for the big two dictates attempts to demonstrate an ability to effect real change. Marvel is in the lead. They've had a string of successes with moves like Civil War, Secret Invasion, and death of Captain America that have demonstrated they can competently progress their universe without alienating people. DC is still struggling with this. This may be an effort to create that sort of progression on their part.
Equally possible is that this is simply a part of some larger plan with Bruce at the end of it. I would wager longer than Knightfall but shorter than five years, as that degree of planning seems extremely unlikely.
A distinct possibly occurred to me earlier, and that is simply that DC doesn't have a plan. They may have adopted a "Wait and see" attitude. Tell a year of Dick Grayson stories, and if it doesn't fly, Bruce comes back as if it was the plan all along. I think this would be a dangerous approach: there
will be venom for Batman's replacement. We've seen in this thread that, for some, the quality of the stories ahead isn't the issue--some will simply hate the books because Bruce Wayne isn't Batman in them. Even if this is a minority, it may create a kneejerk reaction at DC that kills Dick's chances as Batman. That would be bad.