Hey, I'll help. I'm working on the WWII game, so I'll give ya all the futuristic ideas you could ever want!

Just a moment, and I'll edit this post with a simple sketch and description of one idea...
EDIT:
Ok, hope my quick drawing doesn't make the idea seem stupid, but the US military is actually planning and even prototyping some designs similar to this:

Basically, it's a very light "half-track" truck, which makes it fast and capable of traversing everything from rough/soggy/marshy/sandy terrain, to urban environments (even full of rubble and debris). In the future, armor will be stronger but lighter, allowing such vehicles to be tough and swift on their feet... uhhh.. wheels and/or tracks, lol.
It would carry at least a driver and weapons operator. It should have really good suspension, and the weapons would use gyros for stability (helps for shooting on the move). The rear hatch could open up to allow it to carry a few men or equipment. You could even use it to haul heavy things like large guns or mobile rocket launch pads.
For the weapons, it just depends on *how* futuristic you're going for. The guns could be real guns, or even some sort of laser type weapon. Of course, the rockets should be some sort of "smart" rockets, aka guided ordnance. How big and powerful you want them would determine how many it carries. Those could be used for killing vehicles, destroying buildings, aircraft, whatever. They would probably be the most "realistic" as vehicle killers though.
The armor should be angular/sloped, or faceted. Angular armor is tougher than flat armor, because the angle actually makes it thicker when rounds impact it. Look up "relative armor thickness" for a better explanation, or click here:
http://www.panzerworld.net/relativearmour.htmlSomething like this should be pretty fast. Maybe 60-75mph on roads and 45-55 on normal terrain. Slower, of course, in really rough and mushy terrain. But that depends on how big and heavy you want to make it. I think it would be best as a light assault truck though.
Hope you like it, and hope the drawing didn't spoil the concept, lol. But things like this are actually being planned.