You contradict yourself in your linked comment. Add-on install will not be locked to addons.mozilla.org. You can continue to use automatic signing and distribute through whatever channels you like, just as the comment you're replying to states.
> Add-on install will not be locked to addons.mozilla.org. You can continue to use automatic signing and distribute through whatever channels you like
Extensions which require signing by uploading to addons.mozilla.org are controlled by Mozilla and can be blocklisted, it does not matter from where the user ends up downloading the extension.
This practice is worse than what is allowed in Chrome. Google allows installing local and private extensions that have not been signed, after an option is changed in Chrome.