Autonomous aircraft might start being built in 15 years (highly unlikely) but it will be another 30 years until they start replacing all the ones coming off the production line right now, let alone all of the ones currently parked up. Now let's add in the time frame for upgrading airport infrastructure/ATC to deal with them, another 10 years? New joiners have a myriad of things to be concerned about, being replaced by robots any time soon isn't one of them.