Many people are concerned about Apple's ongoing attempts to take more and more control of end user machines from their users. Some go so far as to say that Apple won't be happy until they have absolute and total control over all programs running on end user devices, presumably so that they can enforce their 30% tax on every piece of software. Whether this is true or not we don't really know.
What we can do instead is a thought experiment. If that was their end goal, how would they achieve it? What steps would they take to obtain this absolute control? Let's speculate.