I just don't see how the entire genre of giant robots/mechs, be they Gundam or Battletech, can ever be made to be all that more plausible than they are now...which is to say, hardly at all. A bipedal design is inherently unstable by its very nature, particularly over the sort of rough terrain that a combat vehicle would be expected to deal with. (Just take a look around the animal kingdom...notice how few species besides us rely on nothing more than two legs? Animorphs had a good point there.
) Every sort of current prototype I've seen for autonomous mechanized sorts of units has had at least four legs (like that eerily lifelike military prototype whose video floats around a lot), with some going straight to six. It gives you that much more of a stable test bed without making the gyroscopic problem even more horrendously complex, and it's more capable of picking its way over loose slag and steep hills without completely toppling over. This becomes all the more crucial when you're talking about the sorts of scales that most of these universes tend to deal with. If you can tell me how a two-legged mech on the order of ten to fifteen meters tall that weighs dozens of tons can plausibly cover any sort of terrain faster than an M-1 Abrams, no matter what sort of powerplant is driving it, I'd love to hear it.
So...yeah. Mechs in general are a terribly fun concept, but I'm not holding my breath for them.