This is really an interesting discussion, I have to say.
My 4yo loves Frozen, has asked for both an Ironman fancy dress and an Elsa dress for upcoming birthday, launches into "let it go" regularly around the house, and is just as happy wearing a fireman's outfit or a princess outfit.
That would be my 4yo DS. 
I've given him some lovely floral scarves that he uses as superhero capes, skirts, dresses, long hair (draped over his head).. whatever he fancies when he is playing. If he's having fun and using his imagination (and playing safely obviously), then that's really all I'm worried about.
My DD (who is now an adult) refused to wear anything pink once she hit about 3yo. She is in her late 20's now and still will not wear anything pink or frilly, although she wears dresses as she likes them, just not pink. She was very particular in her clothing choices growing up and was determined to find things that other people weren't wearing so she scoured secondhand shops to find clothing that she liked and kind of developed her own style.
The thing I have an issue with is people that actively discourage their children to wear specific gender related things or Disney things, and push them towards other clothing, but then say "I want them to make their own choices and be unique." Yeah, well, how are they making their own choices if YOU'RE telling them what to wear?? How is that any better? DD had some items of clothing when she was young that "the other kids were wearing too" but she gradually shifted into things that she personally liked. My only influence was that it couldn't be horrendously expensive (as we couldn't afford it) and it had to be presentable (as in not too short, not sleazy looking, and so on).
I'm not sure I quite understand the stress over gender stuff in children. IMO it can sometimes be the parent projecting their own issues onto what their children wear or play with, in their stress that a child will be "indoctrinated" or unduly gender influenced.