> like cavalry in the tank era

Ehhh, tanks are the cavalry of the tank era. Cavalry did not go away, it changed from its namesake horses to armoured battle vehicles but its task remains more or less the same. Drones and 'cheap-ish' ballistic missiles can make life harder for the mentioned expensive high-tech weaponry until cost-effective counter-measures are widely available. For drones that'll probably end up being directed energy weapons - lasers and the likes - while ballistic weaponry can (for now) be countered by moving out of their (ballistic) path. Eventually aircraft carriers will probably be replaced by multiple drone carriers, that may happen sooner or later depending on how the current fleets end up performing in coming conflicts.