They've already said that they're going to keep on doing Uncharted until they're sick of it. Their other team is going to be the team that creates new IPs.
When did they say that? After 3? I would have been sick of it after that, but who knows. I guess I'm more excited for ND's B-team then. Nothing against the Uncharted games, they're great, but after so many you just want something new from people so talented.