I doubt whether there will be an increase in people wearing them, though. Body shapes determine the people who'll wear slacks, and I think those who like wearing skirts will strongly resist them.

I've only ever seen one girl in Japan wear slacks as part of a uniform, and she was Muslim, possibly from Malaysia or Indonesia....

Can you believe that at one time in Japan the leading edge of fashion was LONG SKIRTS (the longer the better - Early 1970's). That hasn't been the case for some time but it is enlightening. Part of the issue today is whether or not slacks are an option for girls. If the students are young then factors such as comfort and general acceptability are more or equally important to leading fashion.

Body shapes my left foot! School-girls in skirts are a major source of income for all the anime, comics, and porno industry. Those 3 along with all the old men looking up skirts will make sure slacks never see popularity.

The girls themselves will keep with skirts as long as they are stylish. Blame the likes of Kumi Koda for her "Ero-Kakui/sexy-cool" fads on fashion. heck blame any number of girl groups in the "musical-idol" industry for encouraging young girls to wear skirts, and to make them ever shorter.