Probably the next step is stop targeting safari browsers through programmatic buying, and if the inventory of safari browser users is worthless, publishers will act I think.
Except iPhone (where most usage of Safari comes from) users have consistently shown to be affluent and spend more money than other phone users. They are the exact users every advertiser wants.
You're assuming that because Apple users spend more on App Store or online, means they are the most valuable target for advertising - that makes no sense at all.
Probably the next step is stop targeting safari browsers through programmatic buying, and if the inventory of safari browser users is worthless, publishers will act I think.