NBA already has a female coach.
Spurs make WNBA’s Hammon first female NBA assistant
http://www.nba.com/2014/news/08/05/spurs-becky-hammon.ap/
And the speculation is, she may one day be a head coach.
I think a female NBA coach is much more realistic as women play college and professional basketball. There is not much of a pipeline for female football coaches.
The most likely scenario would be a college coach hiring his daughter as an assistant the way many hire sons and her taking over when the father retires.