That's like saying a magazine doesn't generate revenue, the ads do. It doesn't really make sense. The ads won't exist without the platform, therefore the platform generates revenue.
A better analogy might be television. If a company such as GE produced TVs and also owned a television network (NBC), then selling TVs so people could watch NBC would generate ad revenue but if someone replaces their GE television with a Sony TV, NBC still makes money selling advertisements.
I'm not sure I would describe the television equipment business as the entity generating revenue.
In the Google ad world, it is the ad-network that is generating the revenue, not the phones/tablets/computers that are rendering the ads.
That isn't to say that Google isn't getting revenue from Android, just that it would be odd to attribute the ad-revenue to the device business.
If Google didn't had android they could not access the same revenue stream if there was an alternative OS the only thing they could do is either generate revenue via regular browsing.
Your TV analogy is incorrect because in your case these ads are platform agnostic, a correct analogy would be GE selling smart TV's that allow NBC to display ads outside of it's regular TV broadcasting (which anyone who owns an LG TV knows just how annoying the fuck it is) in this case this capability is platform specific meaning NBC can only display these types of ads on GE smart TV's if some one has a Sony TV NBC can't display these ads hence NBC can't make money on selling those specific advertisements.
Google ads are delivered either via web pages or as ads in apps. In both cases the owner of the page/app decides which ad network they'll use. There is plenty of competition in ads space.
The situation is the same on iOS, where Google has no leverage, yet they have the same revenue stream from ads.
The only advantage Google has is the default search engine setting on official Google Android phones.
SO you
without ads, magazine will be just fine. people still pay for that.