If rolled out widely, this would make web browsers and third-party YouTube clients without a DRM license unusable for YouTube playback, download, etc. This would include almost all open-source web browsers and almost all third-party YouTube clients. Archive link to reddit post about this
Only if there was no client-side decoration/measurement code/links etc to denote that an ad is playing, which there will always be.
It’s basically no different from having in-stream ads today.
It’s very different. It’s not as trivial as you paint it. They can make it as hard as they want to detect.
I’m not making it out to be trivial, but I am realistic about the matter.
You can have in-stream ads to make things ‘unblockable’, but only so long as there’s no other side effects. Any side effects can be detected, that’s really just the reality of the matter.