Well, I had to go for my own main's mainspec, didn't I? We're now getting into some specs that aren't getting changed all that radically. Protection will, in some ways, be very similar, and in other ways be totally different.
The main culprit is the loss of Holy Power. HoPo is now Ret-only, much as Chi is now Windwalker-only. Instead of tracking resources, we'll be more concerned with the cooldowns on Shield of the Righteous and the new Light of the Protector, which replaces Word of Glory as our self-heal.
Here's the usual caveat - this is Alpha and things are subject to change. Of course, things even change after going live, but generally that's more of a numbers and tuning thing rather than an ability design level.
Let's talk active mitigation abilities first:
Shield of the Righteous remains our go-to AM ability, with 3 charges on a 12-second recharge and no other resource cost. The damage reduction is still 25% baseline, but now lasts 4.5 seconds. Also, with no Word of Glory, there's no Bastion of Glory to stack up.
Light of the Protector is simply a 15-second cooldown ability, healing us for half of our missing health. Naturally, this is more effective when you're on the brink of death, but the relatively short cooldown means you can use it somewhat liberally. It does mean that the days of Bastion-buffed WoGs healing us from 10% to full look like they're coming to an end.
For our offensive abilities, there are some familiar names.
Hammer of the Righteous now fully replaces Crusader Strike. It has 2 charges on a mere 3-second recharge, meaning we'll be able to hit it nearly any time we need it. However, at least at this stage, it only does its AoE damage if we're standing in our Consecration. I'm not really happy with this kind of design, at least unless they allow us to have the Glyph of the Consecrator effect, but there is a talent that fixes it.
Avenger's Shield is pretty much its same old glorious self, with a 15 second cooldown but also the Grand Crusader passive to sometimes reset it. It also now buffs your next Shield of the Righteous or Light of the Protector by 20% - a buff I suspect you'll wan to always keep up (you might even delay those abilities to ensure you have the buff if it's not an emergency.)
Judgment is now on a 12-second cooldown, and oddly there still seems to be the passive Judgments of the Wise, which causes it to generate Holy Power, but since Prot doesn't use HoPo anymore, that can't be the case. Not sure what they'll do with it, but there you go.
Consecration remains, and I believe is unchanged, with a 9-second cooldown and duration. Of course, you'll also need it to buff HotR so that it causes AoE damage. And if you have, like I have, gotten used to Glyph of the Consecrator, there's no guarantee that that will still be available. (Though there is a talent that makes HotR always AoE and have no cooldown, so we might be ok on burst-AoE threat.)
Guardian of Ancient Kings looks unchanged. Ardent Defender has only a 1 minute cooldown, but only heals you back up to 12% if you would take lethal damage. Divine Protection is I think the same as always, or maybe it's the glyphed version? Whatever - it's the 20% to all damage version, and has a 1-minute baseline cooldown, no talent needed.
Divine Steed is a pretty cool new mobility... ability. It's pretty much just Speed of Light, but it's baseline and causes you to mount your Charger (or Kodo or Elekk, presumably, depending on race) for 100% additional speed for 4 seconds on a 1 minute cooldown. And yes, you can use this indoors.
Redoubt is a passive that gives your autoattack critical strikes a chance to give you a charge of Shield of the Righteous or Light of the Protector. That's a little confusing, as currently LotP simply has a 15-second cooldown. I wonder if, like Brewmasters, they'll have the two share charges and recharge, mimicking the way that Shield of the Righteous and Word of Glory currently compete for Holy Power.
So, to break down the rotation, as usual reminding everyone that this does not include talents and artifact traits, which will switch some of this up and add new elements.
1. If you're really low on health, use Light of the Protector.
2. Otherwise, just use Shield of the Righteous.
2. Avenger's Shield (especially on procs)
4. Hammer of the Righteous.
Just as it's always been, you'll have to juggle cooldowns a bit - though certainly less than in the past, what with Hammer's very short recharge and twin charges.
And on one last note: there's a fun talent called Final Stand, which reduces the cooldown on Divine Shield by 50% and also causes you to taunt any enemy within 15 yards for 8 seconds when you use it. Basically this lets you get rid of the old taunt-and-cancel macro and gives you an awesome AoE taunt coupled with invincibility every 2.5 minutes.