Content specific ads.
Mature content on Twitch has become the hottest of topics as of late especially when it comes to ad space and advertisers in general.
My thought being why can't we have our cake and eat it too? Why isn't there a way to have an adult side of Twitch, Twitch After Dark or something, with ads that would target the specific audiences. Obviously not advocating for full on adult films on the site but a place for the more mature streamers/viewers who want to show content/take in such content.
With the correctly targeted ads for the right age groups I'm sure there would be a boost to revenue across all places. Of course ToS would need to be tweaked and enhanced so that you can have mature content with the correct advertising that comes with that area.