The current paradigm is that someone buys BTSX and then trades it for whatever bitAsset they want, or hold it, etc. Once bitUSD is able to cash out directly via a service like OKPay, Coinbase, BitQuick, coin.mx all of a sudden BTSX just becomes another asset, shares in the BitSharesX exchange, and not currency or a "coin" that it currently is and bitUSD will take over as the universal "coin" like BTC is now.
Will this pave the way for other companies to issue stock on BitSharesX? I hope so.