I've long thought this would be a great idea so I would be interested. Eureka did something not unlike this with their SWAT figures many moons ago.
Two body variants ideally, one with chest rig, one with an H style webbing braces and pouches, useable for many western style armies. You could even make the pouches 'plug n play' if you were clever about the sculpting.
Weapons with attached hands so they can be slotted into sockets on arms. AKM, M16, Galil, FN FAL. Plenty of all those still doing service. Kevlar pots, Soviet M60 helmets, bush hats and berets and you could cover a lot of armies for the price of a few dollies and some weapon and head variants.
Actually I'd really love to see this idea applied to the 1960s. Basic figure in US style fatigues, US helmet, bush hat or beret and a choice of weapons. M1 Garand, FAL, G3, etc. could cover most Latin American armies in one fell swoop, not to mention ARVN and. Host of NATO allies.