Subscriber only collections option.
Have a way to make a set of collections (not every collections playlist) subscription locked. There is a way to make a whole channel subscriber only viewing. Why not have it to where a broadcaster can lock a set of videos for those who chose to support the streamer financially while not taking away from those who can't or choose not to subscribe? In this concept, being able to keep past broadcasts and other uploaded content not in that collection completely open to everyone.
Idea behind it: I like to edit streams and other content into condensed highlights and upload them to Twitch and YouTube, my concept in doing this, is to remove the third step of redirecting subs to another place such as Patreon or Discord for access to videos early. Having a place on Twitch would be much easier to allow subscribers early previewing/first looks on content before it becomes public to everyone. This way it would give another perk to subscribing if this is something the broadcaster does, without forcing the viewer to be apart of another process.
But it's not just limited to the idea of early content viewing, this would also add another option of having permanent subscriber only content in the same way there is sub only streaming.