That ship has sailed. Learn how to prosper in that role or do something else. If you think you can do an OS, go for it. I would like to see a third successful mobile OS.
It's not about competing with Android. It's about bargaining power. If you depend on Google, they can dictate any terms they like. Having an alternative to Android, even a crappy one, sets an upper limit to how hard Google can screw you over.