this would be a cool ending but i feel like it probably won't have a real ending to it.

Of the two this makes the most sense. Satoshi-kun's mother's comment of his father and grandfather being very proud of him in the first series was taken out in most of the dubs so I'm not sure how that would play out so I visualize that Pokemon would end in Satoshi winning the Pokemon League!

i don't know. the only thing that i see is possible is that he ages. he won't stay 10 forever.

It's true and maybe after he ages,a Pokemon series comes,with a new protagonist.

This one sounds the best, because I would believe at that point his goal of becoming a Pokemon Master would be complete.