I suspect they would issue new shares for the US listing to...

I suspect they would issue new shares for the US listing to raise capital. It's purely speculation on my part, but that seams the most likely way to raise funds. They would probably issue shares to current holders too.

ie. Float the company in the US, while converting CSX shares to US shares... they would increase their shareholders and shares on issue and therefore the stock liquidity and also raise funds at the same time.