Exactly. It'll be an unsustainable system if there were 100 million users, yet were the market cap <$1 billion.

This seems like a selfish move by Steemit Inc. to retain holdings, which is in direct contradiction to their stated goals of decentralizing their stake. That was early 2017, absolutely no steps have been taken since. That said, this could be useful to third party developers with a sweeping marketing plan. Even so, the concern is no one can compete with Steemit Inc in the subsidy market, due to their overwhelming RC budget.