500 million people who also won't want to pay $400-$600 for another smart gadget when they have already paid $600 for their iPhone.

At that price point, smart watches will remain a very niche market. Just as niche as $600 watches are today for consumers globally.

Android will end up dominating smart watches. They'll be made in China, and they'll cost $50-$99. That will drive adoption in the hundreds of millions globally.

Yes, we already know that Android will dominate wearables, as they do smartphones. Android simply sells cheaper options. It's a bit irrelevant though because Apple simply needs to cater to its current "small" market and remain highly profitable.

As for the size of the market, I'd expect almost everyone on the planet to want a wearable when you can use one to better monitor your health (heart, blood pressure, sleep, etc), use it as a credit card, remote for lights and garage door opener, key for house, etc.

7 billion people, 7 billion wearables.

Count me out. 7 billion minus 1. First I do not like watches, I have not used one for more than 15 years. Second I do not like single companies to try to steal more and more of our private information. So I do not like single company to monitor my health, my credit card nor my garage door. Pop.

You're a rounding error. A few hundred thousand more people became consumers today.

http://www.worldometers.info/world-population/

8 billion by 2025.