"Apple phones already account for one in every five smartphones sold worldwide. The company rakes in about 92 per cent of the profits in the sector, according to Canaccord Genuity analyst Michael Walkley."

That jumped out at me. I don't know if it's true or not and maybe a lot of people can't afford an iphone, but a lot of people can, and it strikes me that with 4 out of 5 cell phone owners not having an iphone maybe Apple does have more room to grow than the professor suggests (and at pretty hefty margins).