This is something that, given what we're seeing in 5.3, I believe blizzard are going to miss a trick on, where as it could have been something really good.
The frostwolves, one of the reasons it still my favourite orc clan, is because of its standing against gul'dan, its exile from the dark horde, how it was lead by durotan, and how its values passed to Thrall, and Drek'thar, though ancient now, still alive and giving his wisdom.
To me, given the situation with what is happening with orgrimmar, the kor'kron, and how orcs have now become what appears as a defacto badguy for all other races to target, this would have been a perfect time for the frostwolves to step up and do something, be like a frostwolf offensive against the kor'kron, since there values of honor and the true spirit of the horde would be a real wake up call for people to know not all orcs are the enemy.
Well on the subject of it, a friend of mine raised an intresting point with one of lorewalker Chos visions, in how in one of the visions, i think something to do with the titans and the mogu, we see the image of Thrall, Aggra and his son stood before a frostwolf banner. What we thought would be a good idea, was if Thrall doesn't become leader of the horde again, that he instead takes on the duty of the frostwolf chieftain, which is technically is meant to be anyway.
If we don't see anything of the frostwolves in the siege, I'll be disappointed.