Replacing races would kinda screw up folk's builds and spawn yet more rampant rqing.
I doubt 3 races involved the client and server support for it just isn't there for that.
However I can see it easily being one new race - with two new classes/jobs (trinity).
In any case the scope of this would require a new code drop from PW Korea since is is something that can't be kicked in with simple configuration like most updates..