Well a GPLed ETQW would be definitely awesome, as that game has some much potential, but was ultimately so flawed at release (and still is I think) that it is not really worth playing

But given the history of scource release of only strictly in house titles I highly doubt that this will happen.

The Quake3 source code however included changes made for the expansion pack Team-Arena, thus maybe some changes have been merged back into the Doom3 code which gets released.