It would definitely change things in a big way - especially for services that rely on acquiring user data in order to be profitable, as you mention. However, I

It would definitely change things in a big way - especially for services that rely on acquiring user data in order to be profitable, as you mention. However, I don't agree that Privly would necessarily end the current set-up entirely. It might result in a little more bargaining power for users who, up until now, haven't had any leverage in the user-host relationship. One outcome that doesn't mean the end of user data-based businesses is where they modify their 'terms of use' to restrict or ban the use of this service. In this case, it's not clear how users could wrest back much control over their information, however.