I believe a few more updates actually made their way into the next PTR (some potentially still in progress):
--Obliteration now causes Howling Blast to grant Killing Machine, as well as Frost Strike. This should help with feeling like you can use Rime procs without interfering with Obliteration.
--The overall damage buff is 21%, not 27%. Just a new estimate of what's correct to roughly account for all the talent changes. Rest assured the goal is to find the accurate amount by which the talent changes would hurt total DPS and correct for that, even before looking into possible further adjustments for class balance.
Finally, the L75 row is generally redesigned. The overall situation seemed to be that Permafrost did a rather low amount of shielding, but was usually taken because the other options had so little use. Some of this might be a little preliminary, but the ideas on PTR are:
--Permafrost shields for 75% of autoattack damage (from 30%).
--White Walker redesigned to: "Wraith Walk cools down 100% more quickly anytime no enemy is within 10 yards."
--New talent Inexorable Assault (replacing Volatile Shielding): "For every 2 seconds spent in combat without melee attacking, you gain a stack of Inexorable Assault. Each stack causes your next autoattack to deal additional Frost damage."
(PTR numbers might vary slightly from the above)
Both of the new talents are going in a direction we want to better explore on slow melee specs like Frost: helping to address time off target, without power-creeping general movement capability. Overall, sprints and gap closers are very prevalent on melee specs (likely too much so across the game), and it's been increasingly hard to deliver on slower, heavy-hitter melee archetypes. Most of that discussion is much longer-term, but I wanted to give some context for trying to resist the direction of having every melee spec use a short-cooldown sprint/charge, and try to branch out into more class-appropriate ways of dealing with the problem.
updated blue post from the 7.3 frost discussion....yes...howling blast granting km is totally not what is needed....but i guess it does make it better....