the better female characters will be written, even if the big companies (DC and Marvel) don't acknowledge that.
The best way to improve the situation is to drop the inadequate aging business plan those companies are using.
Retailers don't want to take comic books featuring girls? Fine. Let's sell on the web.
And let's stop refusing to learn the lessons from japanese comics.
I agree that this whole american distribution system is weird (specially because it doesn't work that way here in Brazil). It seems that the big two are kind of "hostages" of this system, and can't change.
But with digital distributon (through Comixology), this situation is starting to change. DC, for example, now put his weekly comics onlin a few hours before they hit the shelves of comic shops. Of course that made the owners very unhappey and they complained a lot.
DC also has about ten digital-first titles, which are published every week online, and then, only in the end of the month, they're collected in paper.
But this is a problem for the whole comics market, not specifically regarding female characters, creators or readers. It's a system, IMO, that doesn't attract new readers (male or female) at all, just the same old folks who already buy comics.