The second major black swan event is when the US dollar hyperinflates and becomes worthless as a day to day currency. In my opinion this is the more likely outcome.

It would be wise to have multiple stable market pegged assets like in Bitshares (Gold and BTC come to mind), and allow users to choose in which currency they want to receive their payout. That way when the USD spins out of control, people will naturally decide to convert their SBD holdings to Steem Gold or Steem BTC or both and change their payment preference to receive half their payout in Steem Gold or Steem BTC. Since all these assets are backed by Steem, the conversion of one asset into another can be done by the network. That would make Steem the modern equivalent of the philosopher's stone :)