The simplest version of making your channel membership more open will be through a frame.

1. Pin the frame as the top cast in your channel

2. A user who isn't a member can click on the frame

3. Frame calls relevant APIs — token-gating, spam filtering, etc. — and the immediately invites any qualifying user to the channel.

4. So while there won't be a formal "request to join channel" built-in to Warpcast, the design allows for any developer to build channel gating software on day 1. 

5. This can also be used in conjunction with other moderation software (since we will now allow up to 10 moderators per channel). Use one tool for membership gating and another content moderation (if that's what you want to do), and use the other 8 moderation slots for people heavily invested in your community.

Would you use a “subscribe to newsletter to join channel” frame?

cma.xyz. Founder /paragraph, ceo /mirror, previously at Google & Coinbase 

I would not. Just because you subscribe to my newsletter doesn't mean you won't spam the channel. I remember when you first launched the Paragraph frame, the Outcasters newsletter was flooded with fake subscribers