Here Blizzard have shared only their idea for the Rogue class in general....no details.
-Assassination themed around poisons,
-Subtlety around ninjas,
-Combat has more of a pirate/swashbuckler feel."
We can just guess how this will end, but for me the main change will be with the Combat rogues and the idea of pirates....this will attract with no doubt.....the players between 8 and 12 years old, but this is not something bad.
I think that it's a very good idea to change a bit the pure DPS classes, so I can't wait to see the new Pirate PVP Combat Rogue..
The change for priests is quite interesting, but the information is not enough to predict how this will affect the overall priest gameplay.
This is the idea that Blizzard have: " Discipline Priests are becoming more of an offensive healer. They will sustain healing through DPS, with another spin at the Atonement mechanic. Example: throw out single-target heals that place a buff on players, and the next time you Smite, they get healing. Players actively manage which buffs to refresh and make decisions as they go."
If this works as I think it would...Discip Priests will be the main choise for Arena healer in the new expansion. Trust me it's very hard to play against the now, so I can't even imagine how it would be if they become even more flexible in the next expansion.
In general very good change for the Priests and not very good for the players who will play against them.
The Warlock changes in WOW Legion won't be as dramatic as those for the Hunter, but still we will have to change our play style a bit.
According to the information so far, the changes for the Warlock will be mostly about the Demonology Warlocks: "Affliction is master of dots, Destruction is bursty damage, Demonology is a “beast master” Warlock that summons demons, not becomes them--eg no more Metamorphosis. Slides show that Demon Hunters have Meta instead."
So now the Demonology warlocks will need to focus even more on their demons..I hope that they won't fully copy the mechanics of the BM Hunter, but we will see. In general I'm not sure if this is a good or a bad change, but I think that most of the Demonology Warlocks won't be very happy with it.