This looks interesting! Not sure yet how I feel about the (missing) password authentication. Instead a mail with a login code is sent (which seems to work for this.. )
I will try to give you a very brief summary for your points. If you need anything else, just ask a follow up.
- Profitability: We have plans for paid features which are not yet available at this point (kind of micro transactions per jaypad).
- Digital Sustainability (Guaranteeing that the user can use it in the future): To be honest, none. This product is still in beta and as long as it has no sustainable funding it will not have the other one too.
- Interop with other platforms: None at the moment, but we have plans that users can write their own modules for the clipboard side of the jaypad which will open a whole new universe of interop with other things (kind of like Slack-Bots with GUI).
- Privacy: You have the link you have access. It's that simple. But one of the planed paid features is privacy related (no access without invitation, read/write restrictions, private areas, etc.).
On the point "how this platform compares to others":
Think of it as a combination of single-Slack-channel/WhatsApp-Group-Chat on the one side and a EtherPad/Doodle/DropBox on the other side.
Separate noisy chat from writing down facts and stuff you would like to be able to access later on (try this in a WhatsApp-Chat or Slack-channel).