If nothing happens to replace or reinstate youtube-dl, a lot of people like you and me are simply cut off from video content. This is pretty much terrible.
Useful things that I can't do on through youtube's web interface:
1 - archive videos (so many videos have been taken down and would be lost forever to me had I not had an offline archive of them)
2 - quickly play through a ton of videos on demand, offline, without waiting to load the video (and the ads) -- skimming through dozens of offline videos takes seconds, but I'd have to stare at my browser loading forever to accomplish the same thing through a web browser
3 - make use of many useful features of powerful media players like mpv... just yesterday I needed to invert the colors on a screencast because I was watching it at night and the video's white window background was blinding me.. I could do this instantly in mpv, but absolutely impossible on youtube
4 - remix the video or otherwise alter it to my needs using powerful offline video editors.. youtube's offerings here are again a sad joke in comparison (as are most web tools compared to offline tools)
5 - not have to sit through a single stinking ad
If youtube could have just offered simple download links for their videos this would not be a problem.
But, no, they need you to be glued to their website and bound hand and foot to their service for as many hours of the day as they can bleed out of you.
6 - listen to public talks, presentations and soundscapes while doing something else with my mobile device, or letting the screen sleep in my pocket. YouTube requires the video to be on-screen or it stops playing, which makes it completely useless for listening to things. Other video sites are much better for this.
(I don't need advice on how to get around this thanks, I already know how to. But that's another of YouTube's crappy standard behaviours.)
YouTube's web interface is basically useless for me on a slow link, not to mention it's incredibly obnoxious with all its recommendations and other unmanagable propaganda delivery.
Youtube-dl's ability to retrieve titles and descriptions without showing me anything else and before retrieving any video content alone make youtube's opaque hashed URLs usable for me.
I've never used youtube-dl. How do you find the videos to download?
I also have a small collection of youtube channels bookmarked at their /videos URL, which at least doesn't try play any video and just gives a grid of thumbnails. Occasionally I'll visit those to discover new videos from the creators I'm interested in.
This already consumes more time watching youtube content than I care to admit.