Several changes are going to hit your protection spec warrior. First up, you will no longer have Anticipation to increase your defense: it's all from gear now. Secondly, with the change to block value from strength, a lot of your tanking gear that didn't have strength on it now will. Unfortunately, in many cases the itemization that added strength to your tanking gear to increase its threat generation (in some cases you'll see an easy 200 to 300 more block value on the same gear pre to post patch, and that's not even counting all the other ways strength is going to add to your threat gen) comes out of existing stats, and in some cases that means defense rating.
If you like to ride the defense goal of 490 defense right now, and especially if you're using Anticipation (new Patch 3.0.2/Wrath version link) to get you there, you may seriously have to reconsider your gearing. For myself, I just flipped around a few pieces for my highest defense options, but I noticed the drop: a set that used to net me an easy 500 defense without even trying required me to use a defense rating cloak to make up the difference to 490.
That's the bad news for the protection tree. Now for the good news: the rest of the tree is stone cold awesome. No, really. It's so good.You will not be able to get all the good stuff in prot and spend points elsewhere at 70, that's how good it is. When you spec prot, you will be asking yourself Should I spend the points to get up to Damage Shield now or head over into fury for Armored to the Teeth? You'll probably take both. Warriors who can push 800 or so block value on live will gain an easy 200 to 300 SBV as soon as the patch hits. It will be simple to gear for 800 block value, you won't really have to try very hard. And when you do, you will be dealing 180 damage every time you block or are hit while tanking. Meanwhile, Armored to the Teeth is going to increase the damage on your now-global Thunder Clap (the strength on your gear will also add to this, as TC now scales with AP and you'll have more with all that strength... my warrior in full tanking gear is seeing AP around 1300 unbuffed in T5/T6 level gear) meaning that once you can get the mobs hitting you, not only will they hit you less often thanks to TC's slowing effect, they'll damage themselves every time they do or every time you block them.
Honestly, the difficulty here is not in finding good protection talents you can spec into, it's in picking which ones to talk to you about now. Some of these talents (like Gag Order) only get really good once you have abilities you won't get until later levels, but it's hard to dislike an extra 10% damage on Shield Slam. Warbringer all by itself will change the way you play. Combined with the new TC and Damage Shield, as long as you have a relatively good clear zone to fight in, protection spec warriors will be flinging themselves into packs and immediately putting that rage gained to use grabbing threat. Healer pulls aggro trying to keep you up when you do this, you say? It'll be harder with Vigilance giving your 10% of his threat.
Soloing no longer huge pain in the butt
It's not just the way you tank that will be changing. Pretty much every spell and effect you use now to generate threat will be changing from a threat added ability to one that deals more damage instead. You will be able to solo and grind in full prot gear and do respectable, sometimes even incredible damage with a charge/thunder clap/shockwave/shield slam combo. You won't out-DPS the DPS warriors while doing it, but you'll have the ability to pull groups, keep them stunned and slowed, and let them kill themselves on your damage shield while smashing at them very, very hard with your shield. Heck, I haven't even mentioned Incite yet.
In order to get the 51 point talent Shockwave, you're going to be down to ten points left to spend. Frankly, that's a hard ten point choice. Do you get full Deflection? Down to five. Do you then go over and grab Cruelty for the extra 5% crit, or the aforementioned Armored to the Teeth for the threat boost? Since you'll probably have Incite jacking up your HS, TC and Cleave critical rates by 15%, you might want to wait on full Cruelty for a while and just go 5 arms/ 5 fury, getting full AttT and 2/5 cruelty. This is especially true if you also take Toughness, because that 10% additional armor you get from the talent becomes direct threat for your TC and Heroic Strikes and Revenges. In addition, Improved Revenge actually adds damage to your Revenges now, making it a much better talent than before. (Not that it was bad, but most bosses are immune to stuns, meaning that the damage increase adds overall viability to the talent.)
A Well Rounded Tree at last
As I previously said, protection sees one bad change (less defense on tanking gear) but please don't take that to mean that the new Anticipation is bad. 5% dodge that low in the tree isn't bad at all: I might personally prefer that it get the 3 talent point/6% treatment other talents have recieved, but I'd have to admit that's not terribly likely and the talent is a strong one.
In general, protection sees major improvements. Defiance is gone, the threat boost just folded into Defensive Stance but this just frees up points which you're going to need to get everything (and I frankly think Incite's 15% crit boost to both HS and TC makes it the effective replacement to Defiance) and the expertise from the talent has been folded into Vitality. You were going to take Vitality anyway. Warrior tanking viability will be fine, in my opinion significantly improved, with more threat from damage (which, as Ghostcrawler has pointed out, scales better with gear improvements than static threat) and far more multi-mob viability. Warriors will need to learn to depend less on Shield Block to proc Revenge, yes, but with the changes to the Crushing Blow mechanic (it requires a mob 4 levels higher than you to crush you, not 3 as is currently the case in live) you're not going to take crushes while tanking boss-level mobs, and specific bosses (like, say, Illidan) won't use abilities that require a block (like, say, Shear) meaning that SB is free to become a panic button ability. Revenge will require more watching, but it'll hit much harder when it does happen, and you don't need to worry about 103% combined avoidance to be uncrushable. This also means that the occasional critical hit if you're not quite at 490 defense isn't as huge a problem as it used to be since you won't be getting two different kinds of huge spike melee damage, but I still recommend making sure critis are pushed off the table: your healers will thank you.
Okay, that covers protection pretty effectively. But what about arms and fury, you ask? Well, the round-up is so long that we're breaking it up into two parts, and tomorrow we'll cover DPS and PvP warriors and the changes they can expect pretty extensively. I am sad to say that there's less to gush about there. Then next week, it's back to gear for Wrath.