Well it would be mean that God is not faithful, for starters.
Exactly, so why did God choose the prophecies as he did? What would have happened if he hadn't?
Here's my take on it.
God knew how we would advance technologically. He knew how we would progress. The nation of Israel could not have been formed, in say the Eighteenth or Nineteenth centuries.
There were not enough Global influences to enable it to happen. The Bible predicts many Jews returning to Israel by air. Not possible until air travel had been invented and developed.
Also God wants to save as many of us as possible. Until printing became accessible to Christian countries, there could have been no mass production of Bibles.
Also, thanks to telecommunications, radio, TV and so on, the gospel can now be preached to every corner of the Earth.
And so on.....
If the End Times were delayed now, we would suffer unnecessarily. It would be a constant struggle of good and evil. God would be dithering if he had made his decisions differently, but he is perfect and has made the perfect plan.
God has given us a period of grace to show us how we can't manage without him, but to give us chance to try, so that we can't ever question it again.
If this cycle was allowed to continue the wars would get worse and worse. I don't think Islam would take over the entire World but it would take over most of it, and reach a flash point which would probably trigger off World War Three and maybe a Global thermonuclear war. Many other souls would be lost as Islam took over more territory and blocked access to scripture. Israel would be trapped in an endless struggle for survival with countless more Israeli and Palestinian deaths in an endless cycle of birth, death, birth and death.
Decadence would completely consume the Globe with homosexuality, Atheism, New Age religions, Marxism and all sorts of other depravities. God would have abandoned us when we most needed him and his creation would be in danger of destroying itself as Satan just continued the fight to obliterate everyone.
That's why God had a plan that would be triggered into action once the Jews had their own state again. He is trying to show us that we need him and cannot function under our own laws.
He is giving us our last chances to turn back to him, before he unleashes the final test the Tribulation.
If he had decided to delay his prophecies now, not only would he break his promise but we wouldn't be able to hold out much longer.
We've managed for nearly two thousand years of grace but that's only because the Holy Spirit, the restrainer has kept evil on a leash. Now the leash is no longer tight so there is no going back.