I gotta agree that Ash is a heavily marketable human and it's easier for them to build on someone they've known since the anime began. But its pretty silly to be talking about what they'll do next without basis. The whole "target audience" thing seems kinda moot. If everything is new to new viewers then how are they supposed to figure whats trendy and popular on a long-term scale? Its simply not efficient enough to focus on only the short term. If the anime is to continue long term and prosper in doing so, then they'll need to transform the "its for kids" mindset to "the audience deserves better". They jumped the short hurdle, now its time to raise the bar and aim for the high one.
I am the current leader of Save Our Voice Actors, a Pokemon fan group supporting the voice actors in the anime dubbed by 4Kids (seasons 1-8). Our goal is to provide The Pokemon Company international with encouraging feedback in support of returning the main cast members. If you're interested, please visit us at facebook.com/saveourvoiceactors