I think so far nothing was even said about their balance of closed vs open parts. Let's hope there will be as little closed parts as possible. Especially in the UX area. Closed drivers can be probably expected (it's just close to impossible to get open drivers from the manufacturers). But having open UX will ensure that this system will live on. Closed ones (like Harmattan) just die out, when the company can't develop it anymore for whatever reason.