Both the Army's Bradley Fighting Vehicle and the Marine's Amphibious Assault vehicle are capable of traversing water without landing craft. But, neither makes it out of the single digits in knots per hour speed, which means that some sort of landing craft still has to get the vehicles close to shore before they can be used in this manner.
The Marine Expeditionary Fighting Vehicle, is a moderately armored vehicle in the class of the Bradley and Amphibious Assault vehicle in terms of armor, weapontry and the number of infantry it can carry, which is designed to cut of the landing craft middle man, moving the vehicle at 36 miles per hour, which is about the cruising speed of a typical U.S. Navy ship. Of course, this comes with a price (about $7-8 million each, which is three times that of a comprable less amphibious vehicle, although the appropriate comparison would include the landing craft that must accompany the current models), but the real concern until now had been that this technologically risky effort might fail entirely. The MEFV and the V-22 Osprey have been the lynch pin of plans for future Marine stategy, but no one really knew if the engineers could pull it off. Now, the first 25 of expeditionary fighting vehicles have entered production and should enter active service three years from now. This suggests that the risk that the technology will fail entirely is now much diminished.
Together, these two high risk technologies could mean a quite significant change in how the Marines operate. Their main goal is to keep their ships over the horizon, out of range of enemy direct and artillery fire, and even unnoticed by less sophisticated opponents. The V-22, with its much longer range, compared to existing helicopters, could even permit many deployments which must now be made from ships in order to get helicopters close enough, to be made from more distant land bases.
While no formal plans are underway to do so, one could even imagine a few squadrons of Marine seaplanes landing at sea thirty miles from shore and discharging MEFV's into the water for a mission, and then flying off, keeping the "tail" of the force even further out of harm's way and allowing Marines to get to a conflict faster than any ship could.