From what I've read, I believe they are profitable (even with the WNBA's creative calculations) if you include the new media rights deal. The NBA would need to take a much smaller cut to get the players to 50% of basketball related revenue.
If they aren't willing to do that I am fully on board with the players starting their own league. Get some billionaires to help start it up and hire some elite executives to make it as profitable as possible while still paying the players 50% of basketball related revenue. This league would get all of the best talent.
Then if the NBA still wants a piece of the action it can buy the league out (as long as the players approve the sale).
Once you start setting this in motion I expect the WNBA and NBA will be far more motivated. I think the players would even happily accept a path to 50% of basketball related revenue within 5 years.