Well, having done Protection Paladins, it seems like I can take care of another one of my main characters' mainspecs. DK Frost is actually looking not too different than it is now, with a lot of the same procs and abilities, only that they'll be working in somewhat different ways.
As it is live, and how it has been for a while now, Frost has been kind of two different specs - one that dual-wields and does a bunch of Frost damage, Howling Blast-ing its way across the world, while the other has used a heavy two-hander, destroying enemies with enormous Obliterate crits. In terms of weapon load-out, Frost is getting oriented entirely toward dual-wielding - the other DK specs will have two-handers, but Frost will be the one who dual-wields. For those of us (myself included) who really like the idea of a Death Knight wielding one massive, legendary runeblade and are kind of unhappy with the idea of fighting with two little dinky swords, we can at least take solace in the fact that, in actuality, the artifact swords we get are far from dinky, as they were forged (a bit like Widow's Wail and Oathkeeper from Ice) from the shards of Frostmourne.
There are, I think, two other really big changes that we'll get to before going ability-by-ability. The first is that Runes are now all just that - Runes. No more Blood, Frost, or Unholy Runes. Effectively, all Runes are now the wild-card Death Runes. On the Alpha, these Runes have a kind of icy-blue skull look to them, which is pretty nice for our spec. You will still only be able to regenerate three runes at a time, but they will no longer be paired up. This should make rune management a lot easier, and you will no longer need to game your runes to ensure that you're getting the right kind from talents like Runic Empowerment.
The other is that each spec now has its own, exclusive disease. Frost will keep Frost Fever, but that is now the only one that needs to be maintained. As such, this means that things like Outbreak or Unholy Blight will not really be necessary - you'll still be hitting Howling Blast a bunch in your rotation, and since you have no other diseases, you'll have things ticking as much as you need.
Overall, my best guess of how the rotation is going to work (baseline, before talents) is that it will be a bit more like the two-handed version we have now, but let's get into the abilities before we really get into it.
Frost Strike remains your main Runic Power dump, dealing Frost damage with both weapons, and of course will then help regenerate Runes if you have Runic Empowerment or Runic Corruption, though you can opt out of this system if you so desire thanks to a new talent. Notably, Frost Strike is no longer tied to the Killing Machine proc, unless you take a particular talent, which I assume is there for people who really don't want the dual-wield rotation to change at all. It costs 20 Runic Power.
Howling Blast still costs 1 Rune, dealing Frost damage to the target and some fraction (not sure what the coefficient will be, but on live I believe it's half) of that damage to any other enemies near the target, and afflicting them all with Frost Fever.
Frost Fever still does Frost Damage over time, every 3 seconds for 30 seconds, and now each time it ticks, it has a chance to give you 5 Runic Power (it doesn't say how much of a chance.)
Obliterate costs 2 Runes and deals a large amount of physical damage with both weapons.
Rime is a passive that gives Obliterate a 45% chance to make your next Howling Blast free and makes it deal 300% additional damage, but the free Howling Blast does not generate Runic Power.
Remorseless Winter is now a damaging ability, and seems to replace Death and Decay for Frost. It costs 2 Runes and has a 20-second cooldown and duration, dealing Frost damage to anyone nearby.
Killing Machine is a passive that gives your auto-attacks a chance to make your next Obliterate automatically crit. So, same as before, but not affecting Frost strike baseline. Notably, there is one talent that makes it affect Frost Strike, but there's another that makes Obliterate deal additional Frost damage when this procs, which should help the Obliterate build scale with all your stats.
Icebound Fortitude is now Frost-exclusive, but only reduces incoming damage by 20% (and still grants immunity to stuns.)
Pillar of Frost is free, on a 1-minute cooldown, and increases Strength by 20% for 20 seconds and provides immunity to knockback effects.
Empower Rune Weapon is now on a 3-minute cooldown, reactivating all Runes and generating 25 Runic Power.
Mastery: Frozen Heart looks the same, increasing Frost damage dealt.
Without looking at talents or artifact traits, there's another question to ask before we can figure out the rotation: whether to spend most of our Runes on spamming Howling Blast or Obliterate. This is absolutely a tuning thing, and thus something that is guaranteed to change in testing. But right now, HB is listed as scaling with 38.52% attack power (we're assuming single-target here, and discounting Frost Fever, as we'll assume that you're at least maintaining that.) It looks like Obliterate is hitting for 258% AP with each weapon, for a total of 516% AP. That is a hell of a lot more, though HB will scale with mastery at all times. We also need to take into account that HB is half the cost of Obliterate, and thus you can get two for the price of one (though you also pay with an extra Global Cooldown.) Still, even if we assume that you've got an enormous amount of mastery, like at 100%, your two Howling Blasts are going to only do about 160% AP. Mind you, I might have this totally wrong - I'm not a theorycrafter. But as I see it, you're going to be spending your Runes on Obliterate by default. So let's put together the rotation!
1. Pillar of Frost (this is more of a cooldown, but it's only 1-minute, and if you hit it every time you'll have a 33% uptime.)
2. Maintain Frost Fever
3. Maintain Remorseless Winter (this will probably be good enough even in single-target situations, though we'll have to wait to see the numbers.)
4. Howling Blast if you have a Rime proc.
5. Obliterate if you have a Killing Machine proc.
6. Frost Strike if you're at 80 Runic Power or above.
8. Frost Strike.
You'll want to have at least three of your Runes on cooldown at all times so that you're making use of that regeneration. For multi-target situations, depending on the coefficient on secondary targets, you'll start to want to just spam Howling Blast instead of Obliterate (though I'd expect not until you're dealing with 5 or more enemies, given the massive power of both Obliterate and the Rime proc it grants.) Remorseless WInter will definitely be used in multi-target situations, though it remains to be seen how powerful it will be. Assuming it's on-par with Death and Decay, though (and remember that it also scales with Mastery) you'll probably be using it in any multi-target situation, or even possibly in single-target situations.