If the 'open' android model is so great then won't they inevitably win?
No, because the effects of openness, or lack thereof, are very long term ... just as smoking, or lack of it, just as eating lots of candy or not. Even if "open" is so great, people choose shiny/tasty (i.e. short term gains) over "open" all the time.
This is actually the greatest example of capitalism I've ever seen or heard.
In corner A we've got companies that benefit from closed gardens. In corner B that want to keep the Internet free, because they recognize that it's an essential ingredient to their bottom line.
That's how capitalism should work, that's how consumers benefit; and YES, the market will decide. We are used to companies lobbying for their own selfish interest, but in this case we've got companies on both sides, which will make the consumers voices heard.
The only question is, what do you gain from a the closed iPhone environment? If you're an iPhone developer, why do you fear an "open model"? Wouldn't you be happier in that environment?
Myself, both as a consumer and as a developer, I know I would be happier.