If Steemit Inc are considering leaving they should at least make it gradual rather than unexpected or simply sell their company to someone else who is willing and able to fill the role.

Exactly. People are worried about Ned dumping his coins, but I think a far more likely scenario is that Steemit.com, along with all its accounts, is sold eventually to some VC. I'm quite certain Ned has been approached at least once by private investors during this bear market.