Well, talking in terms of SPOILERS...

(Yes, you heard right. There are SPOILERS in this post.)

(...SPOILERS!)

I've heard some theories on the subject, though not many beyond the initial speculation. Quite a few of the early advertisements had pictures of a new girl, with none of the original cast members. Some people believed that it would be the end of the original cast, while others said she would be Ash's sole companion. Still others thought that would serve as a side story to the main series as it progressed into the new region.

As for me? I don't have a clue, although I'd like it if the last one was the case. Two Pokemon series > One.

(No more SPOILERS in this post.)

If we're thinking of Brock being funny, it seems to me that it'd be nice if he was more than just comic relief. That serves a purpose, but when he doesn't even do that well, something more is necessary.