A poster on World of Raids has posted these notes he claims were on the EU PTR forums. There is a whole host of changes in these notes. Quite frankly, there are so many changes listed here that I don't believe they're accurate. This is a lot to change considering how much was changed in 2.3, especially while also doing a major content patch including the Sunwell Plateau. However, I am not remotely psychic, and I'm wrong all the time, so for those of you who love pondering patch notes here's some gristle to chew on.
If these notes are accurate, they're going to try and re-introduce the 'silence and interrupt diminishing returns' idea, entirely redesign how backpacks work, change the human diplomacy racial so that it also increases healing received by 3% (this is the change that most sets off my 'no freaking way' meter), bear tank druids will see their self heal buffed by the healing gear they're all not wearing while tanking, shamans will find Windfury Weapon and Windfury Totem to be nerfed, and prot warriors will be hitting with both weapons on Devastates, which I would personally love to see in my stocking come patch 2.4, but I remember them trying this once. They said then that it did damage 'far in excess' of what they expected, and let me tell you, I was on those PTR's and they're not kidding. All this in addition to a major content push? It seems far-fetched to me.
Still, you may see more plausibility here than I do. Go take a look and tell us what you think.