When the new WoW expansion hits the market you can make worgen/goblin races.
That also means there would be new realm first titles to get.
What you could do is have a level 80 horde or alliance and do a faction change.
When you do a faction change you'll get to pick a new race for your char meaning you can pick a worgen/goblin.
I'm not sure if this works i was just thinking about doing this when Cataclysm hits the market.