The idea of heroic badges is continuing.
It's not finalized yet so exactly what happens is sill up for change and I can't make any definite statements of how it will work, but right now it looks like this:
Unlike TBC, some instances (read: the raids) look like they'll each have their own unique tokens (in addition to heroic tokens). I think the idea is, you can only get so far off of mindless heroic runs (rather than having a full set of Tier 5/6 gear like you can right now) -- and you have a little more "guaranteed" gear advancement in the raids. By this I mean.. if you can down a boss in Naxx every reset you WILL eventually get something good from tokens for that raid even if that one boss doesn't drop anything for you.
Other things are going onto a token system as well. Tier V (Blue-Quality WotLK) jewelcrafting recipes will be available for a kind a jewelcrafting token that you get for doing dailies, etc. The idea takes quite a bit of the luck out of getting gear, because if you have the time/skill to do dailies/defeat a couple bosses -- you can eventually gear up. At the same time, if you're only in Naxx you can only get Naxx-grade items in exchange for tokens (or heroic grade items for heroic tokens, etc).
The current heroic "badge" (to be replaced by tokens through the token system) will likely remain in the game, but will NOT be used for WotLK gear. New tokens will be introduced for those, so dont think you can gear up right away by hammering level 70 heroic instances.
Again though -- level 80 isnt accessible. Even playing the beta first hand, I don't know what's going to happen in the final live release. All we really have to go by are statements by Blizzard, a "Tokens" interface that was introduced a few builds ago (that you need to use the console to open), and a few primitive/unbalanced items that are in the data files but havn't gotten a final name yet and currently read something like -- "[Instance] Token Tank Shield"