While I don't think the appeal of the WNBA will grow considerably, the league won't die. And it shouldn't. The fact of the matter is that very few pro sports teams make money at any level or in any game. They exist for other reasons, chief of which is the ego boost owners get from ownership. If the NBA thinks it has fat that should be trimmed, it should chop the D-League long before it whacks the WNBA. At least the WNBA is different. It offers the sporting public and society at large something new. The NBADL -- or whatever it's called -- is a thorough waste of time and money. Those who hope for and/or predict the demise of the WNBA should focus their attention elsewhere in the NBA realm.
Having said all of that, I don't think the marketplace has a moral obligation to support any particular group of athletes. The WUSA failed in its first attempt because of its hubris -- specifically its belief that it could guilt-trip the American sports fan into paying up to $20 for a ticket to a sport it had never really supported in this country.