The latest version of iOS will have an “Intelligent Tracking Prevention” system built into Safari that not only blocks 3rd party cookies (the common ad trackers) but also various 1st party cookies (which are supposed to be for logins, preferences, site usage tracking, etc.) that also do ad tracking.
Apple doesn’t care about this. Sure they have an online ad platform, but they are a hardware and service company. And their services cost money, so they don’t rely on financial support from crappy remarketing ads. Some of their biggest competitors, like Google and Microsoft, happen to rely pretty heavily (in Google’s case, exclusively) on the ad model. So it’s also a way to eat into their revenue.
But in the end, this doesn’t matter. It will hurt for a while. Some small mobile advertising networks may crumble because of this… but the industry has been preparing for the death of cookies for years. Logging IP addresses or simply buying the data straight from the telecom providers is the near-term future of online advertising. Because you can always count on this industry to do the most harmful thing to consumers at any expense rather than consider reforming their business model.