I think he's more saying that people will be reluctant and/or unable to completely rethink their apps design and functionality and this will present an opportunity for new developers who build things that are uniquely suited to iOS 7 and beat the old slow-moving incumbents.
"Most [developers] can’t afford to drop support for iOS 6 yet. (Many apps still need to support iOS 5. Some unlucky souls even need to support 4.3.) So they need to design for backwards compatibility, which will be extremely limiting in iOS 7."
