The real solution would be to make users pay for the content, but charging for something that users used to get for "free" is also essentially impossible.
Targeted ads are always dumb as they tend to push an item that you've looked into before purchasing, but never realize that item has been purchased and you are no longer interested. They never get that the person researched item but has not looked for some time for item. Let's now advertise accessories for that item. If it was a fridge, show stainless cleaning items, for dishwasher, show ads for different detergents or other kitchen related items. It's not hard. For whatever reasons, they can't do targeted well. Targeted doesn't work as advertised.
If targeted advertising, as a whole, is banned, you can be pretty damn sure the payout for untargeted will come up—not necessarily to match what targeted is now, but way more than that 10% figure.
Ad spend, in aggregate, doesn't change that much based on new "innovations" in advertising annoyance. If you've still got roughly the same amount of money being spent on untargeted ads, continent-wide, as you do now on targeted, they're going to pay out much closer to parity.
I'd like to see the source of that claim.
E.g. this particular study claims almost the exact opposite: "Targeted ads need to be 100% to 700% more efficient than regular ads to be as profitable": https://www.sciencedirect.com/science/article/pii/S016781162...
Right now why would you spend money on untargeted ads when you have better options.
This could well be true. Unless targeted ads are just flat out banned, at which point the profitability of untargeted ones will rise, as the air (user attention, available space in web pages) is no longer being sucked out of the room by targeted ones.
Also - if by untargeted you mean completely randomly chosen ones, there absolutely is a happy medium - choose them based on the content of the page (I'm browsing for baby wipes and formula? Show me ads for strollers and child car seats, and maybe earplugs and some gift ideas for infants, not for motor oil or landscaping or circular saws). I don't buy the excuse that they are so much less effective - especially if the personally targeted ones are out of the picture.
As a huge bonus, they are comparatively trivial to implement and would provide a way out of the current monopoly were only Google, Facebook and a handful of other "know" what to show you and everyone must make these few greedy incumbents even richer by advertising through them. This would also help fragment what information exists about your habits, so even actors determined to break the law would get less advantages by doing so.
Given that ~98% of Internet users couldn't even articulate what javascript does as part of their browsing experience, the exfiltration and reassembling of their PII via meta-data into sellable profiles for targeted auctions is completely beyond their capacity to comprehend or engage with. Thus consent is de facto ungrantable.
