I'm pretty sure the US had drones before Ukraine occurred. The US does invest in drones. Maybe they will more, but we're probably a little way away from them assuming the role of tanks any time soon.
Small drones do not assume the role of tanks. Drones assume the role of WW1 aircraft: artillery spotters and very light bombing capability. They have this role there because both sides have SAM superiority over the other's airforce.
Drones solve the problem that combat aircraft are too expensive and too easy to shoot down.
I'm not saying they do. I was replying to a comment.
Define "light". Ukraine is fielding FPV drones with EFPs attached that can easily slice into anything armored.
I'm not sure if I'd be rooting for this eventuality.