[CoA] Add 2 new playable races - High Elves and Goblins
CoA is experimental enough as it is, I don't see this suggestion being out of place:
Add 2 new races - High Elves for Alliance and Goblins for Horde on the Rexxar Realm
The reasoning is that these races have been a part of Warcraft story since Warcraft 2, and are still around in WoW - There are a lot of high elf NPCs, and even some towns - in Winterspring, Easter Plaguelands, Hinterlands and ofcourse Terokkar Forest (Allerian Stronghold), possibly a few more that I'm not remembering. Not all elves became addicted to fel magic and followed Kael'Thas or joined the Horde, many stayed faithful to the alliance.
As for the goblins, many of them are still a part of the horde, even if some factions pretend neutrality or value coin above loyalty to any faction, there are lots of goblins that are still working for the horde, and I think they were originally intended to be a part of that faction when WoW was first being worked on - and they did once Cata broke out. They also conveniently have very well animated and detailed models, both Low Definition and High Definition and can easily be made into a playable faction.
There are of course the challenges of making their racial abilities and starting zones, but I think it's one more thing you could exercise your creativity on.