We definitely need a new Titan Metroplex. Not only is the older one hard to get, it wasn't accurate to the game, even if it was promoted as the toy representative of that character.
Also, it was 10 years ago. At the very least, Hasbro could issue a 10th anniversary version, if the mold was still usable. But if that happened, we would probably know about it by now.
I don't think we'll get a game version of Omega, especially with the Guardian coming out, and IIRC he wasn't too different from the G1 version anyway.
Trypticon, on the other hand, was vastly different than the Titan we have, so he could definitely use a toy for the game version.