I watch youtube & movies/series on my HTPC - no live TV.
Regarding numbers of subs - I wouldn't read much into that. There are lots of channels about now with a million+ subs that have been through the lifecycle & are pretty much dormant. I'm subscribed to maybe 300 channels but only regularly watch content from 5 or so.
It will be interesting to see how YouTube grows or if any competitors can take off - The adverts in the last 12 months have become very intrusive, particularly if you've no easy way of blocking them - it's a pain to do on android & probably impossible on anything Apple.
My gut feel is that viewer saturation is not too far away.