The challenge with astral projection is that even with years of military secret ops training, the images are often vague at best. Future travel is further complicated because even with time being immaterial on the astral plane, we are truly not astral beings, and thus have a spiritual block that allows for only possible or likely images instead of the actual thing.
One theory for this is that pertaining to the infinite amount of parallel universes. One may travel to a future, but make a choice in the present that alters that future such that it does not manifest in this timeline.
This is a possible explanation why the vast majority of "prophecies" are vague and open to interpretation; and most usually never materialize.
Occasionally someone will get a glimpse into the future, a strong premonition not to step into that elevator (that crashes right after), or that something horrible will happen to a family member or loved one. The theory with these is that the future is allowed to be seen because the karmic path is so strong that the future cannot be altered - and that this karmic path is allowed to be seen/sensed between two people who have that astral/spiritual connection.
But very rarely does someone see a definitive future many years from now.
Helen Wambach hypnotized thousands of people (psychology students, she was a professor) and not only did past-life regressions, but also future-life. The interesting thing is that almost everyone described one of three futures:
1) Post-apocalyptic - war-torn desolate lands and famine
2) Communal-type spiritual living in a pseudo-utopia
3) No major change from today
But when you think about it, those are basically our three choices right? We degrade as humans and destroy the world, we evolve spiritually, or we stay mostly the same.
So did they truly glimpse the future or just sort of make an educated guess and then let the imaginations go?
Such is likely the case with Astral Projection into the future.