Ash and Misty as Elite Four? I don't think that's probable. Ash remember, is on his journey to be a pokemon master. Their are so many pokemon, that Ash will have to take a long time before he actually becomes a pokemon master.
Have you heard the tale about Ash's Dad? In the beg. of the series it showed a glimpse of Ash with his mom and dad, but didn't show the dad's face.
Ash's dad set out to be a pokemon master, saw the "most amazing things" unimaginable-especially some pokemon discoveries no one even knows "today." What could they have been? Anyhow, Ash's Dad died mysteriously...or did he?..., and so that's why Ash's Mom is worried about Ash a lot (but that doesn't mean that she is just protective ^^) --she is worried that something terrible might happen to Ash.
Haven't you Also wondered why Ash is looked up to by the legendaries? Ash possesses some ancient aura that links to the pokemon and which will save the pokemon from a destruction that will occur...in the future. What could this atrosoty be?
...The author hasn't revealed yet.
Well that's it, I hope this get's you guy's thinking ^^