Metrotitan would bomb. He never appeared in a cartoon, and can't really be tied in as an eHobby exclusive (Twincast, Guardian Robot). I wouldn't get it.

As for some of the moulds not released, I don't think TT see restoring some of them as viable. We know Sunstreaker & Wheeljack are lost. Convoy (Prime) was also lost, but they know they'd be able to milk that one to cover the R&D Cost.

At this stage I think the most realistic "new" reissues would be:

Piranacon, Trypticon (both moulds used fairly recently)
Eject & Rewind if they can work out how to package them
Trailbreaker, Thrust, Ramjet (limited about 6 years ago)
Dirge, Bluestreak, Red Alert, Grapple, Hoist (not mass released in Japan, only limited a few years back)

All the above moulds should still exist. Along with the Bruticus mould, but there are far too many version (real and not so real) out there, they've stated this one wont be happening.

Personally? I'd like to see Shockwave, Sandstorm & Snarl. Along with Fort Max & Liokaiser for everyone else to get (: