I think you're right that drones are increasingly replacing heavy troops because of their effectiveness against light troops. Heavy troops will eventually adapt, whether that's by some kind of advanced anti-air system or jamming them or using other drones/aircraft against them....all of which are expensive solutions. Light troops go for quick, cheap solutions like using hospitals as shields, which only works if there's a hospital near strategic locations or you're fighting someone who cares about collateral damage.

I suppose what that says about museums is that the smaller ones may be able to quickly adapt to technology if they can find low cost solutions, and that the larger ones have the resources to develop more comprehensive adaptations but it will take them lots of time. With technology advancing at an exponential rate, they might not be able to keep up.