2015's Terminator: Genisys attempted to reboot the Terminator franchise for modern audiences by attempting to reset the events depicted in the first movie, 1984's The Terminator. Unfortunately, because of an oversight by the movies creative team (co-writers Patrick Lussier and Laeta Kalogridis, director Alan Taylor and producer David Ellison), the events depicted in the movie, chronicled in the Genisys Timeline, do not correlate with any of the events depicted in The Terminator, or any of the Preliminary Timelines.
As explained in Time Displacement Explained and The Cameron Paradox the Terminator movie franchise adheres to the theoretical principles of causal time travel. Yet Terminator: Genisys' depiction of its timeline(s) not only fail to adhere to the theoretical principles of causal time travel, it also fails to adhere to the theoretical principles of alternate reality/timeline time travel.
In Terminator: Genisys we are seemingly shown two timelines. In the first of these timeline's Judgment Day occurred August 29th, 1997. It is also shown that in this timeline Kyle Reese was in possession of a photograph of Sarah Connor. In virtually all respects this timeline mirrors that of the second timeline, the timeline from which the Terminator and Kyle Reese originated from in The Terminator. However, before John Connor could send a reprogrammed Terminator back in time to 1994 Terminator: Genisys depicted John and his Tech-Comm unit being attacked by the physical embodiment of Skynet who had successfully infiltrated Johns inner circle, posing as a Human Resistance soldier.
The second timeline depicted in Terminator: Genisys is that within which most of the movie is set. In this timeline, the reprogrammed Terminator and T-1000 prototype that should have been (but were never) sent back in time to 1994 were instead sent to 1974. Saving a young Sarah Connor from termination the reprogrammed Terminator became Sarah's guardian, and presumably having been sent after another iteration of the timeline whereby the Terminator and Kyle Reese had been sent back in time to 1984 before it was sent back in time, was aware of the exact date, time and location in which both would arrive. This allowed the Guardian Terminator and Sarah to prepare for their arrival and to destroy the Terminator, thus ensuring that no surviving evidence of the Terminator would be used to hasten Miles Bennett Dysons understanding of Artificial Intelligence. As a result, Cyberdyne Systems never become a technological giant and subsequently its work was never adopted by the USAF's Cyber Research Systems division. Instead, Cyberdyne Systems development into AI would have occurred at a natural technological rate, if it was not for the arrival of John Connor in 2014.
It is later inferred that the second timeline depicted in Terminator: Genisys is in actuality the same timeline as the first, this would suggest that the depicted 2029, 1984 and 2017 scenes are all part of a predestination paradox similar to that depicted in The Terminator. However, the reprogrammed Terminator and the T-1000's presence in the "second" timeline does not adhere to the aforementioned predestination paradox because of John Connor's subjugation by Skynet while Kyle Reese was being transported back to 1984. Together with John Connor's existence, despite having never being conceived, the timeline(s) depicted in Terminator: Genisys do not adhere to the causality of the events depicted in any of the previous timelines of the Terminator movie franchise, or for that matter the causality of its own narrative.