Great point. We’re launching with a clear Fair Usage Policy to address exactly that—preventing abuse (like the "filesystem" hack) while keeping it truly unlimited for actual team communication. Our cost structure is different than legacy players; because we’re built on Cloudflare + our custom CRDT-hybrid store, the overhead for storing and searching text is low enough that we can avoid those arbitrary 90-day or 2-year cutoffs without it being a sustainability risk. We’ll be publishing our explicit "human use" guidelines on the site soon so there’s no "shadow" cap anxiety for legitimate teams.
Just sell extra storage at reasonable price. That's the most transparent system you can get.
Some users will never hit more than few GBs as it will be near only text. Other people will share 100MB video clips daily or use it as easy way to transfer files betweeen users in company
Maybe have option to expire attachements at separate timer or ability to set a cap where oldest files get removed if it is passed for cost-control-concious companies
Your costs will change and shift over time. Personally, I don't trust anything that says "Free Forever" or "Unlimited". Give a real limit and figure out the transition. "Free now, and no plans to change, but if it does, we will give you one year to transition" is much more confidence building then "Free forever".
Gmail has been free forever :) even when google wasn't the behemoth it is now