"It’s hard to say at this point, but it could be the case. For Tekken Tag Tournament 2, even though the name says Tag, you can play one-on-one [as you can in the traditional Tekken games] and you can play two-on-one, so it is already kind of merged into this one game. It could be the case that this setup will be the standard [for our games] in the future. It will be hard to say until the game comes out." - producer Katsuhiro Harada

In other words, ideas brought forth in the Tag series could become regular elements of the mainline series, eliminating the need for a Tekken Tag Tournament 3. Man, TTT2 isn't even out yet and we're talking about the next!