Women's final went to Sunday night due to weather delays. It wouldn't have mattered who was in the final. Based on how TV rights were bid and shared between ESPN/Disney family and CBS, there was no way a Sunday night final would've been shown on CBS. Legal agreements in the contract stipulated that the match be shown on ESPN family channel then. Unless of course you're saying CBS would then step in (just based on Williams sister presence) and pay extra money to cover ESPN's contract fees; which I highly doubt. CBS already lost so much money due to rain downtime waste on Friday and Saturday. Their execs would be out of mind to shell out extra money at the last minute. Also the time for the match would be so difficult to advertise, given that the remaining time window was very narrow. It's plausible, but highly unlikely IMHO.