I was also wondering about this very same thing, i have not played on the PTR so i can not comment about Frosts new mastery but i would also like to know if Frost will still be the 'PvP' spec played by mages. Although i am very sad to see Frostburn outed, i am curious as to how our new Icicles will affect Frosts PvP gameplay.
Iv watch some of Venrukis stream when he plays on the ptr and it seemed to make no difference overall, one thing i did see was him using his deep defensively or to cc healers on kills. Since our mastery is now not effected by frozen targets it will be nice to be able to use Deep other then offensively without it being such a huge penalty.