Youtube has kind of killed some things for me, but made other things better. Bicycle videos on YT have watered down the sport and devalued good content via dvds. At the same time given coverage to riders i'd of never got to watch, but you still have to filter through the junk and over produced stuff to find the good stuff (imo). So in that regard it's a net loss.
Gaming, again, plus and negs. Secrets and easter eggs have lost value to being spread everywhere, but being able to watch good content reviews is a plus. Also Twitch is junk, and is also owned by a toxic company, so YT streaming i did prefer. So a net gain imo for gaming.
Vimeo is worth a look at, if trying to avoid the junk.
YT is good for finding music, which then i can purchase from the artist and support them. So that's good in one sense, but harms artists because people don't all think the same. But then smaller artists are given coverage, which then i can also go over to Bandcamp and follow them there. So a net plus.
As for movies (streaming), i still buy dvds, i'd rather have the copy i can do whatever with and know i've got decent quality. I have considered purchasing a streaming video from YT, but never bothered because i'm a sting with my money.
As for YT replacing TV, yeah, no, maybe. Internet radio and podcasts, as well as music, dvds, killed TV for me. But 20mins to kill quickly, yeah YT has that covered well, but i'd happily watch the news if TV licence was free...
My real problem with YT is trying to filter out the rubbish and try and find the good stuff, which is quite tiresome in itself so i often give up. It's why i ditched Netflix pretty quickly.
For society, i think YT could happily replace TV, people have shown themselves to binge on whatever is put in front of them.