the opening MD will still be given to hunters, I feel - a rogue's ranged DPS isn't the same, and those initial hunter shots will always be needed to get the initial threat set in.
Of course, it now means that there'll be no chance of the tank losing aggro.

I can actually hear it now - a rogue being called to "TotTy" the boss when it looks like someone else's getting too near on threat

That's only on par with how Blizzard thinks these days. Every single buff/debuff should apparently be able to come from at least 2 classes/specs. Only logical that rogues, the masters of trickery, gets it.

Also remember that BoS is gone, and threat generation has been changed somewhat. I'm pretty sure we'll need both MD and this thingie regardless of what sort of tank we got.

I don't see hunters will quit being called on to Misdirect any time soon. We'll still be designated pullers. It really means that we will have another group who can help add threat to the tank during a fight. And help us direct traffic a bit when a mob goes nuts.

Now Blizzard. How about buffing our Misdirects with a nice damage bonus or a "How ever many times you can hit in 6 seconds" condition to match?

Fights like Anetheron will still call for a hunter. When an add shows up and is dangerous in melee except for the tank who is designed to survive it, then a hunter is key.

Rogues also won't have rhinos blocking building entrances... ;)