All of the listed services will still be there, they just won't be making excess profits for their owners.
Which is exactly what FLoC is a step towards fixing. It may not be as perfect as not having any targeted ads at all, but it's a much better than the current status quo
As for targeted ads, I would argue that most advertising would be non-viable without it. Yes, something like Coca-Cola won't care, but your average small business owner who needs to target a specific niche will basically be unable to advertise it.
Imagine I build an app specifically for people into biking, or into animal crossing, or into some other small niche that's less than 0.1% of the population. How do you propose I grow my audience without any sort of targeting at all?
The cases you state can easily be marketed to using contextual targeting, e.g. displaying ads on biking websites or communities or individual pages that contain the keyword "Animal Crossing". All of that is already possible and doesn't require any data on the user.