If Laura never existed and/or never murdered, then neither Cooper nor the FBI would never have been in TP in the first place - that being said, Cooper would not even know the name Laura Palmer or know her house. Basically, in my opinion this nullifies the finale
I'm done - we got trolled - already had to block a bunch of people on Twitter who wrote to me saying I am not a true Lynch fan if I didn't like the finale lol
In the words of tulpa Diane; F**K you inter web trolls