In this short (under four-minute) video essay John Green talks about YouTube Red -- which basically gives you ad-free YouTube and some exclusive content for $10 a month -- and what that might mean for the future of YouTube. John and his brother Hank operate a fairly successful YouTube empire and he knows what he's talking about. (John is also a successful novelist.)
YouTube is currently supported by advertising, some of which is shared with content creators like John. For some this can be a nice piece of income, but for most it isn't, and rumor has it that it's been declining. (For a very rough estimate of the range of income a channel might be making, go to this page and enter the YouTuber's name.)
YouTube Red will probably be a bit better than ad-revenue sharing for content creators, but for all but the most popular channels there's vastly more income potential from Patreon (a way to make voluntary donations), from separate sponsorship deals (ads that are actually part of the videos), and from sale of merchandise. Healthcare Triage, for example, gets significant support from Patreon, and Film Riot has in-video commercials and a store selling everything from T-shirts to music and sound effects.