Yes, BitUSD, like litecoin, dogecoin and darkcoin, will likely be among the first cryptos to be exchanged for BRO.
But "instead" of BRO?  Consider these related issues.

1. BitUSD's tie to USD is good as a steady unit of account to purchase merchandise, but it hardly seems well matched for those who choose to be in the crypto and gaming community, for which BRO is designed.  For any gamers who don't want the volatility, they can cash-out of BRO when they choose.  For those who welcome the risk for potential gain, BitUSD offers... about the least variability possible.

2. BRO is inherently a global coin. USD, while being the "world's reserve currency", isn't everybody's base currency. Around 2/3 of fiat to crypto exchange involves CNY.  While BitShares is leading edge, BitUSD locks its users to the fiat banking system's flagship, the USD.

3. BitUSD implements the BitShares structure created for widely varied, distributed autonomous companies.  As such BitUSD lacks the many selected coin features of BRO, like improved Proof-of-Stake, privacy options, fixed block rewards, etc.  Reading through the list, you'll see what the BitUSD holders would be missing.