Tanking in the future!
Warriors are and will probably continue to be the baseline on which other classes and their tanking abilities are determined. The effectiveness of any other tank will be compared to warriors - how good are they at multi-mob tanking compared to warriors? How well can they take a tremendous beating from a melee boss compared to a warrior? How effective are they at total mitigation, magic based damage, gimmick fights, snap aggro, tauntless mobs, etc etc etc. I see Paladins and Druids coming forward more at MT positions and, with the Death Knight, a new form of tanking will arrive that is superior to baseline warrior tanking in some respects but lacks their general tanking viability in order to preserve the balance. Eventually I expect all other tanks will shake out as being better than warriors in a specific aspect of tanking, and what will keep warriors in their accustomed tanking role will be this baseline function. The class may well become the #2 tank in every possible contingency... less effective than paladins at AoE, less effective than druids at massive burst damage fights, less effective than death knights at (let's pretend we know anything about how they will tank) pure avoidance. What the warrior will have is a wider range of abilities and greater depth in their assortment of tools for both aggro and mitigation, filling a tanking role similar to the way priests fill all the possible healing strategies.
Furthermore, I think what's really going to keep warriors tanking is that there's a great community of theorycrafters, old hands and so on in the warrior class that have spent a lot of time studying tanking, going out and doing the job and reporting back on what works and what doesn't. This and general expectation from other players will keep warriors tanking at least in five mans and heroics (most people don't really sit down and consider 'what is the best tank for this particular instance' or even 'what is the best tank for this particular boss' the way a raid group will) but in raids, you'll see more tank swapping as the four different tank classes are used to min-max the chances for raid success. I expect, in fact, that the idea of a 'main tank' will recede to a degree, perhaps becoming more of a raid-leader's title than actually being the person who tanks most of a raid's encounters. You'll see specific tanks being used because their particular abilities make them most suited to a particular fight, perhaps even leading groups to bring a tank of each tanking class or more of the already seen swapping of specific tanks in and out of a raid to ensure they have the right one for a particular fight. And yes, this will diminish the importance of raiding warrior tanks. But with four tanking classes in the expansion, I don't see how it could be otherwise, as raiding guilds are going to bring the people to the fight who can most easily get them through it. I think warriors will adapt to this as they always have.
Beyond the veil of time comes the DPS warrior of tomorrow!
One thing I expect we'll see as a result of the expansion is, as before, warriors being one of the most dominant classes in terms of population. Since we have so many warriors now, many of those warriors will be raced through the expansion to reach level 80 and begin the new endgame, whether that means killing Malygos or facing Arthas or what have you. However, with tanking now being split between four classes and warriors being the baseline tanking class (perhaps best at single target tanking as they have been up to now) we're going to see a shift in what warriors are used for in raids. If raiding continues as it has been, there will be a lot of fights with no CC or limited CC (perhaps some shackling or ice trapping, the occasional sheep or sap allowable) and the easiest way around such a situation is to have offtanks, characters that can tank when necessary and who can provide DPS when tanking isn't necessary. I expect to see warriors, feral druids and perhaps retribution paladins (ret/prot hybrids, perhaps) taking on some of these roles.
I expect that rogues will continue to be the highest DPS melee class, but we've seen that warriors can be competitive in the role of melee DPS, sometimes even coming out on top in specific fights. With the changes to fury in 2.3 that allowed whirlwind to hit with both weapons and gave fury warriors a greatly extended sweeping strikes, it's still my belief that fury warriors are being aimed at the 'melee AoE' niche and will be used in that role on trash pulls as well as being expected to get and keep a set of tanking gear for specific fights when, alongside other classes capable of tanking, they will be performing in this role as an OT/CC solution. In general I expect fury to become the 'swiss army knife' spec for raiding, providing boosted shouts for a melee group, doing AoE damage with sweeping strikes and whirlwind, and serving as offtanks when there's no other form of CC available.
The future is a season 6 boot stepping on your face forever - warriors in PvP
No amount of nerfing is ever going to get rid of PvP warriors. Warriors continued to PvP when the Arcanite Reaper lost its king of the BG's role following weapon normalization. Warriors continued to PvP when rage was normalized. Warriors will continue to find ways to excel in PvP no matter what happens to the class. If the entire arms tree was removed tomorrow and a new tree named "Carebear" was added, warriors would find a way to use Carebear spec to smash faces in PvP.
For one thing, PvP is extremely warrior friendly. We have high health, meaning we can survive a high DPS attack from a caster longer, letting healers do their job and keep us up. We have talents that specifically allow us to resist or reflect damaging spells if we're fast on a macro. We have high armor, so we can reduce incoming damage from physical damage classes. We have a good assortment of abilities to close the gap in combat and to prevent others from running from us. Even if you took away mace spec tomorrow, there would still be warriors atop the PvP ranks, screaming incoherently and smashing faces with whatever weapon seemed best to them.
There have always been warriors in PvP, making videos that conveniently leave out all the sheepings, ice trappings, gougings, death coilings, intimidation stunnings, paladin bubbles and so on. There always will be warriors in PvP. They're not going anywhere. They will be nerfed, and they will keep doing it anyway.
What else lies in store for the warrior of tomorrow? Well, I expect those protection spec soloing improvements, as one of the ways Blizzard will have learned from The Burning Crusade. I expect that the new talents for each tree, if new talents come in, will help refine each spec and I would be very surprised if fury didn't get more AoE damage options, perhaps even a way to AoE in CC without breaking it or a Bladestorm ability. I would not be surprised to see Prot get more DPS and I'm outright praying that the static threat abilities get a major threat buff or an overhaul to the entire system. And maybe, just maybe, Arms will finally get the ability to dual wield 2h weapons. Yes, it would be overpowered if they could DW 2h weapons at the highest iLevels, but a level 70 warrior DWing Sulfuras and Ashkandi wouldn't be OP and could squeeze just a little more use out of those older weapons they'd otherwise have to ditch.
Okay, I know the dual wielding 2h'ers isn't going to happen. Let a man dream!
Next week, either we talk about dealing damage in PvE and PvP, or we talk about stupid warrior tricks, those weird uses for warrior abilities that aren't really powerful or overwhelming, just fun or odd.