The future in the flashforwards is Reality 1, in which people seen in the future did not already know that they would have that future - i.e., had not seen flashforwards six months earlier. In other words, no flashfowards had occurred in that Reality 1.
But the moment the flashforwards do occur, that changes Reality 1 into Reality 2, in which everyone alive knows that flashforwards occurred, and most people have seen themselves in their flashforward.
That is the reality which our characters are living through now, and we are seeing unfold each week on television.
Which suggests that the flashforwards can indeed be changed, though not easily.
Of course, since in our reality there are no flashforwards (as far as we know), we are just living in reality, with no number.
But see FlashForward 1.9: Shelter from the Storm
See also FlashForward Debuts and Oceanic Airlines as a Portal Between FlashForward and Lost and 1.2: Proofs and Defiance of Inevitability and 1.3: Conficting Visions and Futures and 1.4: FlashForward Meets Shaft and House ... Drunk FlashForwarding in 1.5 ... Across the Universe in FlashForward 1.6 ... FlashForward 1.7: The Future Can Be...
Listen to 40-minute interview with Robert J. Sawyer
The Plot to Save Socrates
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