Keep in mind that unexpectedly is different than soon or quickly. He said it would occur unexpectedly and soon, within the very generation he was addressing. John and other disciples spoke of the Antichrist ALREADY with them and that the end was near. Jesus in Revelations states that the end times would bring a recompense to repay those for what they had done to him, (Rev 22:12 revised standard edition). Again that meant it was coming to those who were physically involved in his death and the rejection of his message and who refused to believe that he was the messiah whom the Jews were expecting and failed to recognize.
THE PHYSICAL RETURN OF JESUS
What is equally surprising to many Christians is not only that the end times have already occurred, but that Jesus has already returned physically in the flesh as well. Paradoxically, while the Jews missed the coming of their messiah, the Christians recognized him, but then they missed recognizing his expected physical return.
The Jews still await their physical messiah, and ironically, after almost 2,000 years, Christians are still awaiting the bodily return of Jesus. Jesus has already returned physically to his disciples exactly as he promised he would.
After the crucifixion he startled them all as he came to them in his very physical body. They did not believe he was flesh and blood when they first saw him again. They asserted to him that he must be a spirit. But he corrected their mis-interpretation and let them know that he was physical and not a spirit.
However, they were skeptical so he showed them his physical wounds. Still they did not believe him, so he challenged them to touch him physically. He further had to prove to them that he physically returned by asking them if they had any food because he was hungry and they all sat down and ate fish and drank wine together.
However, his physical return was not some special physical vision that only his disciples and those close to him were able to witness. The Bible states that hundreds of people also witnessed that Jesus returned physically in the flesh after the crucifixion and his death on the cross. The Bible is very clear on these accounts. Jesus returned early to his disciples as he promised.