I believe that airdrops are far from over, as they are the method that most projects find to attract attention, reward users and reinforce the decentralization of a project
It should last a few more years, but I think it can always “revive” when there are good, decent projects worth investing in
Airdrops are also part of the cycle, where most altcoins are performing badly, and if there is an altseason, airdrops should improve considerably