This is what I mean, NRS NEEDS to clarify whether MK9 is either an "Alternate Reality" as some imply it to be, or a "different timeline". Alternate Realities are where the events may already be different before gaining knowledge of the future, whereas a different timeline is where the events are the same until someone gains knowledge of the future.
That's what I take from it at least. If MK9 was INDEED an "Alternate Reality" then okay fine, there are no Retcons, such as Kuai's motivation for revenge, Lin Kuei on Shang Tsung's side, Kung Lao participating in the first tournament, etc. But if MK9 was a different timeline ONLY, then those events I just mentioned, prior to Raiden getting his visions, ARE retcons.
I think the majority of people implied that MK9 was just a different timeline, but now the question of "Alternate Realities" kind of makes things different.