Law of unintended consequences
This should be fun. The Google pinata law is Go. Unfortunately Google can actually handle its data, though they'll definitely have to leave a limb behind. Facebook will be apoplectic that they'll have to allow user data export. Good.
Enforced data export fluidity might be an problem where finding and cleaning the data is the point of the business. Everyone's definitely going to get 'informed consent' fatigue. Cookie banners on steroids that must actively prevent you entering until you agree. Will sites be usable by those who decline? Incognito browsing will bloom barriers every .. single .. time.. and God help you if you're a bot.
But really, this is just a big glorified beta test, and it's going to get very grating for all parties over the next few years, with other nations taking note/advantage. Nobody will get this right for decades.