What if the final episode was just Rose telling a story on how she became a human from beginning to end, and that Steven was Rose Quartz, but just had an amnesia... or Steven becomes full human and Rose comes back
I dont think so, there'd be no point in renewing SU until season 5 like they did if this ep would be final. It's probably something like Steven vs Amethyst, where everyone speculated that there'd be something really really big, but it wasn't that big, it was obviously a very big ep on Steven and Amethyst's bond but it wasn't as serious as most people predicted.
BTW, i believe it will have something to do with understading between humans and gems. Steven might become the "President of Homeworld" or something like that, and the dark past of opression war and death will be switched with peace, love and tolerance.
Gems would visit Earth, while humans would be free to visit Homeworld and meet them.
And as the screen closes in on Rose's face, a few seconds of silence will pass as Rose contemplates the events. All the tragedies, all the rewards, all the success, all the failures, and the miracle that is life and all it entails. And the final words that the series will be remembered by that nail the theme the writers have so carefully been crafting will escape from her lips before the screen fades to black, ending this masterpiece forever.
this will not be the final episode cause there are about 26 episodes per season plus last one out of beach city doesnt seem like the name of a final episode for a show the final episode will probobly be the crystal gems freeing homeworld and bubbling the diamonds or something like that