There were no counters to cavalry for like 1000 years. The only generalized countermeasure to cavalry was cavalry of your own. This led to the dramatic territorial and genetic expansion of nomadic peoples, such as the Arabs and Turks.
There are specific 'counters' like pikes, fortifications etc, but they only trade effectively against head on charges. Cavalry still held the advantage of tactical mobility, which meant they dominated reconnaissance, can pursue and annihilate defeated enemies, can retreat gracefully etc.
There may be no counters to drones except for more drones. Or the counter may have to be highly strategical, such as devastating hack-based attacks that may involve use of advanced and dangerous AIs (Cyberpunk Blackwall...).
Artilleries also had no counter for like 50 years. And completely reshaped military doctrine and strategy, made WW1 into a slog etc. WWII found a way to 'beat' artillery by armored thrusts to get behind them, but that is not easily achievable.
You're right that you may only find a counter to the latest tech once you've lost the war, or you may never find it and you'll only see the victors over you displaced by someone who does find a counter and now rules over you instead of your first enemy.
There are specific 'counters' like pikes, fortifications etc, but they only trade effectively against head on charges. Cavalry still held the advantage of tactical mobility, which meant they dominated reconnaissance, can pursue and annihilate defeated enemies, can retreat gracefully etc.
There may be no counters to drones except for more drones. Or the counter may have to be highly strategical, such as devastating hack-based attacks that may involve use of advanced and dangerous AIs (Cyberpunk Blackwall...).
Artilleries also had no counter for like 50 years. And completely reshaped military doctrine and strategy, made WW1 into a slog etc. WWII found a way to 'beat' artillery by armored thrusts to get behind them, but that is not easily achievable.