Take a look at any Facebook Profile or iPhone Home Screen and you can see how lucrative the closed market is. But with one click your benovolent provider can remove the need for your application by implementing the same application as a native feature. That is to say Apple denying applications to the app store because they are developing the same feature or adding a feature which negates a £4.99 app.
Facebook has done the dirty on the Birthday Reminders Applications, by implementing birthday notifcation into Facebook by default.
This has to be one of the biggest drawbacks to any closed system, you can create something really great. So great infact that the ‘company’ notices and then makes there own version, or something so similar as to avoid lawsuits. Whilst it is true in the past Apple has paid for these features such as CoverFlow and the new visulaiser in iTunes 8. There is nothing to stop them, a small company simply cannot afford to take them on, in such a situation.