you know robotics tech is always advancing, and with enough sensor data control theory and a little ik you can make a walker that is fast and agile. the main problem is control. i made the point the other day that a computer with billions of transistors will not be as good at walking than a brain with trillions of neurons. but if the stuff coming out of darpa is any indication, its a problem we will likely be able to solve.
there are a couple things though. maintenance will likely be more expensive than in wheeled vehicles. more moving parts means more that can go wrong. also i dont think the role for mechs will be front line combat unit. the walkers and powered exoskeleton type suits ("power armor" is kind of a misnomer as the thing just makes you stronger and improves your battlefield endurance, its not a forcefield). with what we've seen come out of darpa in recent years have all had an infantry support role. they carry your gear, your ammo, etc, and for exoskeletons you, a bigger gun, more ammo, maybe some armor, and twice the gear of your standard foot soldier. weve got some way to go before that is used in a front line situation. i also want to point out the complete lack of stealth. a soldier can always get down into some cover, if your strapped into a walker good luck doing that, you had better hope your armor is tougher than their guns, because guess where every enemy weapon will be pointed, right at your toaster ass.
now scale it up to something the size of a tank. you are now tall enough so the enemy has to aim up at you. from the elevated height you will be able to see infantry in their foxholes and deliver ammo upon them. but that wont be your job. no your job will be to shoot at other tanks and walkers. they put billions into the thing and they want their moneys worth. say you have a machine that can walk rough terrain and do it quickly and quietly. but in the case of a bipedal walker you have a much less stable platform than something on treads. since you have less surface in contact with the ground at any given time you better not take it through sand, in swamps or any ground that cant support it. the mech stands up 20 feet high, so it has a highly visible cross section to the guys with rpgs or the a-10s overhead (your entire mech sits in the gau-8's cone of fire nicely). apply the damage of a modern rpg shape charge, or a heavy caliber gun firing depleted uranium shells (or any other armor penetrating round) that can liquify bits of your legs on impact. however your worst enemy will be guerrilla fighters with good intel, shovels and camo nets.
