Replacing witnesses is a social question, its not inbuilt into the protocol to select/pick witnesses, they have to be picked by the users of the system, or if each user doesnt care, then the default hub byteball.org or other hubs can do the choice on behalf of the user.
Its really a design inspired by biology, organic user action is required.
So far only the XSS-finder portabelle has a witness running and it looks like some have selected to use it. Exactly as envisioned.
I am a volunteer to set up and run a witness. Would you replace one of your witnesses by mine in the default list at least until we get some well reputed "captain of industry" to replace me ?
That means : are you socialy ready to start release hands on witnesses ?
Personally, I am ready to place trust in community members.
EDIT: Again the CfBs fear strikes, now reposting same useless pictures. Pathetic.