Less than 20%? Lol. Completely wrong. That’s the global market share...In the United States, the iPhone lineup is close to 50%
Completely wrong? Not at all. First, allow me to point out that, under existing law, a company's geographic market is the market it does business in; for Apple, it includes the entire world. The DOJ can (and often does) argue for a smaller definition, but it has to do so based on issues like transportation costs, customer ability to shop outside their defined area, cross-elasticity of demand, etc. Again, in the instant case, U.S. customers easily have the ability to buy phones from any world manufacturer, with -- compared to the cost of the phone itself -- trivial transport costs.
Secondly, even assuming the DOJ could successfully argue for geographic exclusion, Apple could again cite existing case law, for instance the landmark case
United States vs. Alcoa (148 F.2d 416 (2d Cir. 1945 ), in which a 90% market share was adjudged adequate to constitute monopoly power, but a 64% market share was not. "Nearly 50%" is not nearly enough.
Finally, you ignore the third prong of the legal test, which is that, even after establishing a case of monopoly power in the phone market, the DOJ would have to establish tying; to wit that this is leading to monopolization in the cloud gaming market, a segment which is certainly entirely non-geographic, and which, I assume, Apple's share is even smaller.