Boston Dynamics got started making weird leggy robots specifically for terrain that’s too rough for wheels and tank tracks, so if there was somehow a need for a bipedal robot it might end up looking somewhat like a mech.

My guess is that legged ground based war machines are usually going to have 4+ legs for stability, though. Airborne drones are probably going to be way more common.

Personally, I hope we achieve a utopian future where war is obsolete, scarcity is history, and we build giant mecha robots and battle with them as a power sport