Not at all clear what was supposed to be happening.

I rather think the idea is the whole thing was some kind of near-death experience, in some kind of purgatory in the form of a TV series set in 1973.

In which case the 2007 section was a lie of some kind, a sort of sidetrip into an alternative hellish afterlife, courtesy of The Tempter, the devilish Morgan. And Sam managed to escape back to where he was meant to be, which meant he at last accepted being dead.

Or does anyone have any better ideas?