I disagree with this romanticism that a company should always be built for sustainment. A small company has only two ways of being successful - either disrupt and be radically different or fill in a piece of the puzzle that a bigger company has not achieved. If you look at the nature of the product the Sparrow team developed - an iOS/Mac client - it wasn't radical. So being gobbled up by an appropriate bigger company is natural course for that startup.
So I should read this as all of the small business owners in the world should either just give up or strive to be acquired by ACME corp? I think we have a very different understanding of the word "successful."
Camera and mail apps don't need to be platform-neutral simply because the content and output of those apps are platform-neutral themselves. Mail apps push and pull apps from servers which can be accessed from other outlets/apps. As for camera apps, as long as they are saving a local copy (like Camera roll), other apps will still be able to access those photos. So yes, convenient form of sharing like direct export-from-app may be lost but the real output would still be platform-neutral.
