You guys have to stop and think for a minute about that though. Halo 4 and Halo 3 are VERY different games. Imagine playing team slayer on Guardian in Halo 4. Everyone is sprinting to the other end of the map in less than 3 seconds and using all these armour abilities. It would break the map.
The only maps from Halo 3 that would work on Halo 4 with the redesign are probably The Pit, Construct, Highground (and that's barely making it), Avalanche, Sand Trap and any other bigger map I might have missed.
I just don't think our favourite smaller maps would work with the faster pace of Halo 4 :[[