The Tank and it's future.

[Uesugi Kenshin]

The big advantage I see in a light tank is one of mentality. Instead of IFVs which are battlefield taxis and fire support, tanks are dedicated soley to killing the enemy. Additionally the main cannon of a tank has a bit more ability to destroy enemy positions at long range opposed to lighter guns such as the M2's 25mm which lacks the HE blast of a 105 round. Perhaps if the Army were to bring back 90mm and 106mm recoiless rifles and mount them on humvees (in place of TOWs due to lack of enemy armor in current threat environments) then infantry would be able to have organic direct fire support again. Though this would be with a lack of survivability that even a light tank has over wheeled vehicles.

I think waht you're looking for is the Ontos. That was a beast. http://en.wikipedia.org/wiki/Ontos It may have basically been an M113 with six recoilless rifles slapped on it in a lot of ways, but the thing scared the pants of the NVA and Viet Cong and could bring tremendous firepower on a target with relatively low weight, and the ability to carry some troops. I'm not saying we need something exactly like the Ontos as six recoilless rifles that need to be loaded from outside the vehicle obviously limits the capabilities of an IFV, but something similar with better close quarters capabilities, like a GMG or light cannon, would be great.