I saw a really interesting program last night on TechTV about that if the Army continues down the wheeled vehicle route, they have very interesting drivetrain technologies coming on-line. On a test-bed LAV-type vehicle, they've replaced the transmission with electric motors in each wheel powered by deisel-electric generator. The unit saved several thousand pounds of weight in removing powertrain and the individually powered wheels now have a greater of motion than when connected to an axel / transmission. With shrinking gas turbine technology, it's entirely feasible that all the electrical power and propulsion needs could be supplied by a turbine about the size of a coffee can using just about any flamable gas or liquid.
If this is the route taken, one can only hope that the replace the weight savings with armor because I cannot see these machines running "dodge-em" speed in urban areas.