People need to learn Ash leaving the series won't change anything. It is the writers who matter. Ash can stay and if the writers do it write could change the series into something amazing. just because Ash would leave doe not mean a better series would happen. It would be the same thing even if he was replaced. A series is only as good as the writers.
Looking at the N arc preview it seems the writers might of realize past errors and are working to make it more plot focused. They said they had a big change for the next series so this just might be the start of something good leading into a much better writing system. We saw them try a plot in DP however BW pro to N seemed to go back to the Kanto vibe sadly. Here is hoping they keep going with the dP vibe but build on it
There are two things about the anime that we all know for sure:
1) It won't be ending anytime soon.
2) Ash will not be getting replaced.
Anybody who tries to say otherwise is getting their hopes up way too much. I think the anime is definitely improving though. Black and White has had less filler episodes than the last two generations, and seeing that N is about to come in to the series, I think it's going to get a little series. In my opinion, this shows that the writers have realized the mistakes they made in the past. When the new generation starts, hopefully it will be at least as good as the Indigo League episodes.