The next generation for you and me is when our first child is born. Not usually even 30 years elapses before that happens.
It is evident that the words attributed to Jesus show that the Gospel writer thought the return of Jesus was almost overdue as he wrote ! later in the 1st Century other Bible Books were written because all the early Christians were distraught that the prophecy had not been fulfilled.
Of course the JW org knows much better than all those early Christians and Bible writers, who they claim were inspired by god, and say that all of that "evidently" means what they say it does. The evidence only being that the JW Org says it.