Renegade Legion is one of those oldies but goldies. The Roman styled legions of TOG, the oppressive aliens, the high tech combat both on the ground and in space. It really was a very unique setting and it defiantly would work in 6mm.
Someone mentioned a Recon game, Vietnam time period. While that would be interesting I think Battlefront is already doing it in 15mm and it looks pretty darn good. Also the number of huge battles in Vietnam is actually pretty small so 6mm seems a little too grand for the scale, but I could easily be wrong.
I'm personally still rooting for Robotech, but not due to any knowledge of whats coming or even a logical speculation, just holding onto a dear childhood love I probably never will get over.