I think he's implying there would be no middle market. If you can buy an Android phone for $150, and an iPhone for $600, there would seem to be room for $300 phones, but what justifies a phone running identical software costing twice as much?
Samsung has been able to sell Galaxy S and Note for a premium based with a combination of massive marketing spending, specs (bigger, higher resolution, more cores, more MHz, more RAM, etc.) and features (face unlock, eye scrolling, etc.)
They can't market any harder than they are now, it is already starting to become a joke to even their fans with stuff like the staged selfies during big events, or fails like when they pay celebs to tout their products and that celeb tweets from their iPhone the next day. They've reached a point of diminishing returns in specs (does anyone care about getting a 4K phone or 8 cores, has anyone ever run out of memory on a 3GB phone?) and their last few generations of features have been seen as gimmicks even by the Android faithful.
Apple has a "monopoly" on selling iPhones, if you want one you go to them and pay what they ask if you think it is worth it. Samsung is just another Android OEM, they are trying hard to differentiate with their S-xxxx names of existing Android features but is it working? Why should someone pay much more for a Samsung phone versus a no name brand if they run the same software and do the same things? With each revision Google reduces the ways in which OEMs are allowed to differentiate their offerings, so the noose grows ever tighter.