From what I understand about the whole "John was written around 90Ads", was just a rumor or quote from Eusibus, who knew Poly Carp, who was supposed to know John.
Most of all the Gospels and letters were written between 54AD - 69AD, the Revelation though is highly debated if anything. Thus there are four main views, Historicist view (Which means that the church is going through ages and whatever age you believe you are in is what is happening or something because of the rest of the context of revelation) it is on going history repeating, you have the Idealist view (which means revelation never comes to completion, you have the futurist view (which means people are waiting for Revelation to happen), you also have the preterist (which means everything happened in the past, then there is on other view which is seeing everything fulfilled and it also uses some of preterist views along with of course some historians like Josephus, Tacticus, Suetonius, and Cassio Dio, which all help in seeing the fulfillment of 70AD being the final destruction of Israel for the final and second time, and as the wrath fell down those loyal and faithful Christians in the day in age were looking, watching, waiting for the return and they seen him come save them who was the Bride of Christ in that day in age, fulfilling everything that had be promised when Jesus Christ was on the earth to those people then in that day in age, so that all things would be put underneath his feet, and Jesus would give everything back over to the Father. Having completion, and wrapping the old material age up, by moving in the new spiritual economy that would now follow going on to the Heavenly Realms after dying and passing away. Some to be with God because of faith, and those who did not want anything to do with him, won't be there and won't have anything to do with him because they choose to do so.