iPhones are mainstream and market leader in the US, yes.
In every other region not so much. Here in Western Europe they are far from market leading, though still able to be considered 'mainstream'. But due to the inflation and lack of salary increases here since the 2007 crisis, most people go for midrangers now, and the iPhone SE is not attractive at all (old design, no oled screen). Just looking around on the subway I would see nothing but cheap Chinese phones now, most of the iPhones are from tourists.
In every other region not so much. Here in Western Europe they are far from market leading, though still able to be considered 'mainstream'. But due to the inflation and lack of salary increases here since the 2007 crisis, most people go for midrangers now, and the iPhone SE is not attractive at all (old design, no oled screen). Just looking around on the subway I would see nothing but cheap Chinese phones now, most of the iPhones are from tourists.