Once prepatch goes live, everything that doesn't involve WoD only content like leveling to 100, garrisons, new zones, etc. should go live as well. So new character models, toybox, talent revamp should all be available come prepatch.
Let's see... official post:
http://us.battle.net/wow/en/blog/156825 ... 014#hunter
The relevant line:
"Additionally, Hunters can now tame beasts from new pet families."