Include both AoD endings by using the S-Mart ending as a dream sequence while Ash is asleep.
Cool, the very same idea occurred to me last time Riami made mention of still wanting to do an ED4. I imagined that after Ash woke up from his S-Mart dream the original ending would play out and after Ash screams "I slept too long!" it would cut to black, then "15 Years Later" would fade onto the screen, then off again.
From there the story would pick up with a new set of characters who are being pursued by the unseen force which along the way possesses one of the group members transforming him/her into a particularly nasty deadite creature. They might make some mention of Ash as either some sort of folk hero or as a crazy hermit who thinks he's from the past, in any case the creature finally makes its move on the group and at the very last moment our reluctant hero Ash comes out of nowhere to kick some deadite ass as only he can. It is soon revealed that he has an alterior motive for saving them (food/ammo/they're on his turf/one of them is an attractive woman).
Basically from there the story would continue with the now older Ash, still sporting his crazy beard, explaining to them (and the audience) how he has learned to survive in a post apocalyptic deadite infested future world and that he does not normally engage the deadites and spends most of his time in hiding. At some point later on in the film Ash would finally get his sense of purpose back, shave the beard, suit-up & gear-up in the usual ED/AoD montage we have come to expect.
That's about as far as I got. Anyhoo, back on topic...