Monopoly by definition is a single (or overwhelming) supplier. Vertical integration is about the exact opposite since it opens the business up to competition all along the supply chain. Amazon now competes with almost everybody.
We've had larger firms in retail and other industries in the past that died of natural causes. There is no reason to think different of modern tech companies. These are just the people who are getting the transition we have in the marketplace. Others will see and pick up on it to. You can't judge a monopoly over just a 10 year period of time.