I think maintenance can be done through a DAO, and yes I believe we have many developers who are capable to do what you’ve discussed.

As far as your other comment, I’m not really sure what you mean by that.. all witnesses are independent individuals but some actually run successful businesses and have been responsible for a large amount of Steem’s once success. If someone is needed to “manage” anything, specifics could be hired through the DAO as well.

As far as an actual maintenance number, I do not have that. Sorry 😐