So here's a thought. Mike tells Cooper in his Dougie phase, "You need to wake up!" Here I've been thinking that just meant, "Hey! Snap out of it! Remember who you are! There's important work to do!"
But what if Coop-as-Dougie was literally asleep - and dreaming?
What if everything that happens after Coop steps through the door in the basement of the Great Northern is the dream he's having while he's "asleep" as Dougie. He has his 1989 encounter with Laura Palmer, then the "Richard and Linda" sequence with Diane, then the Carrie Paige encounter... and then I'm guessing it continues for a while into scenes we aren't shown (because he was Dougie for quite a long time).
Not at all sure about this part, but we've all been wondering when he experiences the scene where the giant gives him his "clues." I think it might occur after "Dougie" has electrocuted himself and is lying in a coma. I see it as the final "briefing" he receives before he has to wake up and... do it all over again?
Just to be clear, my idea isn't to negate everything that happened in that final section because "it was only a dream." I think it could be entirely real on some level - I just think Coop might be experiencing it while apparently stumbling around as Dougie.
Thoughts?