The following are some examples of “anāgata (future) rupa.”
1. Suppose person X plans to visit a friend in a nearby city next week. He could visualize how he would travel by car, meet his friend, and have a good time. But the day before his travel, he may be forced to abandon his trip due to a flooding of the highway, a broken bridge connecting the two cities, etc. That is an example without abhisankhara. It could have happened to an Arahant too.
2. In the case of Angulimala, his future would have indicated being born in an apaya upon his death. But the day he met the Buddha, that changed dramatically. Later that day, it would have indicated being born in a “good realm.” Two weeks later, upon attaining the Arahanthood, his future would have indicated not being born in any realm upon death!
3. Trillions of years ago, Buddha Deepankara gave “niyata vivarana” to then Bodhisatta. Buddha Deepankara told the Bodhisatta not only that he will become a Buddha at such a time in the future. Buddha Deepankara told him that he will be born to King Sudddhodana and Queen Mahamaya, be given the name Siddhartha, etc. Our Bodhisatta’s future had been pretty much “fixed” even that far back.
It is good to think about such examples. That is part of “insight meditation.” Feel free to ask questions if any of the above is unclear or if anyone has other unclarified scenarios.