What the modding community needs isn't a developed TC 335a or WoD, or Legion for that matter, what everyone needs is basically a rewritten WoW wordpress-type template engine, like that MMOSDK or some other projects that were never finished.
Problem is only the size of WoW but by now even that doesn't matter I mean just look at the all the forums how many people are doing this its really high time someone develop some template open source something, decrypted and without made up rules like trinity 'must be Blizzlike' and such.
And about the size, it even doesn't have to be too overwhelming if e.g. they made lets say - Azeroth+Kalimdor and 6 basic race classes as a some kind of core, and all other extras can be developed by other people and deposited like wordpress plugins.