In my opinion, Google isn't going after the mobile devices market. They are expanding their share to enhance their online offering. A very simple example is google maps and navigation. The more people using google navigation; the more precise the driving time prediction is going to be. The best way to ensure people are using Google navigation is through google maps apps. In addition, the more people using google navigation api, the better.
With these said, Google may charge license fee. I couldn't see it happening soon unless Google management decides to give a better competitive advantage to Motorola.
On the other hands, Google is primarily delivering Android OS. Apple is selling device with iOS. Samsung is selling device with Android. As of today, Google's Android OS has the biggest market share. Apple devices will always attract fans. Samsung offers the best Android hardware at the moment. To compare all these companies, I feel like comparing Kit-Kat, Apple and chocolate coated strawberry. Just look at product alone, Nexus 5 vs iPhone 5s vs Galaxy S4, everyone can make their own vote. ;)
Definitely, I believe Linux will win in long term just like in the PC world. Nonetheless, the winning doesn't exclude any other OS existence. I am sure Linux based mobile device will get more attention from techies than from non-techies. As of now, Apple will still hold on to the share of non-techies together with some very technical persons. :)
But this doesn't help Google compete with Samsung if they give away their software to Samsung and others. But if they stop doing this they fragment Android and Google just haven't got a large enough market share to go it alone in hardware.
I'm pretty sure that Google don't see themselves as a major competitor to Samsung. Their Nexus line fills a gap in the market for people who want the latest Android technology (geeks basically) rather than the mass consumer market that Samsung aim for. It also ensures that Google are not dependent on third parties to bring their latest software to market. But I don't believe that Google have ever expected to dominate hardware sales. They are primarily a software company and are smart enough to concentrate on doing what they are really good at.
I'm not sure what "winning" means in this context. Android must cost Google a lot to design and maintain but they give it away for free. Even if Android becomes the de facto standard OS for all small devices in the future isn't that something of a pyrric victory? At least Microsoft made money on their monopoly. Google make money from advertising-supported web services. It's not clear why they need to produce an OS to do this.
Also, not all future devices may fit the ad-supported revenue model that Google uses. They make less money from mobile ads than PC ads. Will anyone want ads on a smart watch? How many "things" in the IoT will be capable of displaying ads?
Maybe Google will one day start charging a license fee for Android and become the new Microsoft? But Samsung will probably be their biggest customer and Apple will still be there. So I don't see a single winner here.
Amazon definitely isn't direct competition for Samsung, but they are in some ways competition for Apple & Google, and have an Apple-like concern for ease of use.
They sell media, have well regarded cloud services, an app store, and their own devices -- and a lot of integration. If you're in Amazon Prime, you get a lot of nice bonuses (I'm not, but I know several people who are). On the book side, I'm concerned with their dominance, but I have to give them credit -- they keep on improving the physical Kindle readers (both e-Ink & tablet), and seem to have their act together much more than their competition.