This is a quote that should end in 'yet'. I am very confident in saying there will be an AAA game released that will be designed and implemented 95%+ by a machine. I am less confident in providing a timeline. If you consider the history of machine learning is ~70 years old (in one sense, one can argue other dates) and you plot the advances from tic-tac-toe to what machines can do today (chess being a prime example), it doesn't take much vision to see that it won't be but a matter of time before this is a real thing.