This is just a small selection of games, that run the gamut from quite old to brand new, from f2p to p2p, from indie developers - publishers to big house names. While they've experienced varying degrees of success, most are still more than viable, with old & new players still regularly logging in.
One of the features, which they all have in common, is that some or all of their character classes are gender locked.
Continent of the Ninth (C9)
Dark Blood Online
Path of Exile
Runes of Magic (RoM)
Rosh Online (Karos)
Seven Souls Online (Martial Empires)
Soul of the Ultimate Nation
If Dragon Knights has anywhere near the success of some of these games, then it will have a steady & loyal player base of both genders, playing all available characters or as many as the game will allow, for a good long while.