I think any media reaction would be very short lived. No one in the tv watching/sports media consuming public cares much at all about women's sports in general and the WNBA in particular. After a week of headlines, the story would go away.
The best way to pull the plug on the WNBA would be to do it like ripping off a band aid. Announce at the end of the season that funding for the WNBA would be ended and the league would cease to exist. Weather the week of "outrage" and move on with life.
Yes, media/social media outrage burns hot but doesn't last long. If the NBA was willing to endure a few weeks of bad press, they'd be fine.
I don't think it would impact their bottom line one iota. Obviously, the WNBA was a marketing gimmick by the NBA. I don't know how much it's really benefitted them overall from that perspective.
I think, like you, they could easily back out. They could refer to the recent media rights deal as evidence that the league is ready to stand on its own. Really pump it up, hype the new young players, talk about the huge surge in ratings. All as evidence that they don't need the NBA anymore.
They won't do it though.