Multiple markets being available doesn't mean that multiple markets will survive.
Apple's free to open an Android App Market, with Apple-reviewed apps, and taking a cut for the value they add.
Ultimately, it could become the most popular Android App Market, and a de facto monopoly instead of a de jure one.
That's what open is really about.
Android provides an ecosystem. iDevice provides a homogeneous, crafted population. One evolves by natural selection, the other is a product of intelligent design. Unlike the Flying Spaghetti Monster, Steve will die some day. Then what happens? Android may take longer to "get it right", but just like with biological evolution, rapid uncontrolled iteration will ultimately lead to the fittest solutions.
Motorola, HTC, and Samsung are upping each others' game by competing based upon the value they add with their handset and OS customizations. Sure, right now they're bending over more for the carrier than the end-user, but all it'll take is one viable and open service provider to blow that open.