Of course they knew it was the end. George Martin believed they had already split up after recording the tracks for Let It Be. He was quite surprised when Paul called him up and asked him to produce it "like he used to".It's like they knew the end had come. Despite all the differences and squabbling, they could put that all aside and still come out with arguably their best effort. A fitting end to a phenomenal group that changed the course of music and will stand the test of time forever.