One thing about tanks and one of the reasons I don't think mechs will ever be used is the fact that they require so much support. I think the only way it would be possible would be with micronized nuclear power plants. Today the marine nuclear power plants are fairly small - so a 20' by 8' area would be required, plus shielding. I think tanks are not used very much due to the infrastructure required. So, I would think that in order to have even heavier walking mechs would require even more infrastructure. I'm a big fan of mechs but I believe that they would need to be much larger - something more like an AC-130 Gunship combined with a submarine with 4 or 6 legs. I think mechs in the future would be very large with nuclear reactors allowing them to operate indefinitely in the field without a massive fuel and infrastructure trail. I think your image is awesome, I just think that in the future mechs would be more like walking troop transports with micronized nuclear reactors to remove their fuel and maintenance supply line. I think mechs in the future would have 16 man crews (4 fire teams) and 2-3 pilots with 2 engineers. So the supply line would be with the mech itself. Also, the 16 man squad (4 fire teams; 1 section/squad) would man weapons and guns aboard the mech which would probably be substantial - 2-3 main cannons, 4-6 .50 cal chain/mini guns and then mission specialized pods i.e. missiles, anti-air etc... LOL. Sorry for my long post, I just think a lot about this stuff. To make it short... I think the future mechs will be a cross between a six leg walker with a AC-130 and a submarine.