iPhone also has over 50% market share in Japan, Canada, Denmark, Norway, Australia and more. Currently it doesn't have 50% market share worldwide. But in more countries it is gaining market share.

What does China having 1.4 billion people mean to Google? nothing, because they have chosen not to do business in that country. So the argument is moot. Even people in China who use VPN, install Google Play store on their phone to access banned apps in China. BTW there are 3 billion 30 day active android phones with Google Play. If you take biggest Android appstore in China it doesn't even have 500 million 30 day active users.