LAVs provide light armored RECONAISSANCE as their primary mission.  While the LAV brings a lot to the fight, its small carrying capacity limits its ability as a true mech infantry platform.  Remember the premium the Corps places on strategic and operational mobility, i.e. the ability to deploy quickly to theater, vice tactical mobility, i.e. the ability to displace quickly once there.  Tactical mobility has been provided by helo assets and to a lesser extent by the AAV.  This will be enhanced by the V-22 and if they ever get the program on track, the EFV.  More armored vehicles mean its harder to get to the fight, even if mobility is enhance when one finally gets there.  Anything else will be on an ad-hoc basis, such as with the purchase of the Cheetah, Grizzly, and Buffalo mine-resistant vehicle derivatives (I've forgotten the name of the new Marine model of these that we are buying a butt-ton of.