I doubt that WZ comms will become Basics, unless you exchange them at the vendor.

But NB: There is no way of changing them back.

Speculation is that all PvE comms > basic (i.e. elite and ultimate) will become basic comms, that Basic comms will buy the next level of PvE gear ( 192 probably) The trade-in for elite and ulti will be probably at a bonus rate of maybe 1:2 and 1:3, and you might be able to exceed the comm cap(s) for some time.

WZ comms will likely continue to be used for WZ PvP gear. - Whether there will be a new tier is yet to be announced. - However with the level increase to 65 - there'll be 5 more levels to gain more WZ comms in if you avoid the PvE story.

Whether your Exhumed/ Dark reaver gear will bolster properly (or not) and/or be competitive between levels 60 and 65 is a really big unknown. The is also speculation that mainstats/endurance are going to change. BW don't have a stellar record with Bolster, balance nor support for PvP issues as it is., sad to say.