Steem is not Steem without Steemit, Inc. It would have to be new, unofficial, and a new chain, without @steemit and the existing whales in it. Technically altering the witness code has to include renaming it, at bare minimum, according to the license. Using the same name would not make sense, either. In fact, if a new steem chain is running but not under the responsibility of Steemit, Inc., it would be a violation of their IP.

IP. A rule of the Camarilla, not the free market.