I think that would be nice, but I doubt they will because it would cause a change to how some passive abilities work. As an example: Normally, a lightning main will not benefit from Jiraiya's buff because it is male, but being able to switch it to female would change that.

I would like that though, for the sake of added options and versatility for all of the mains if nothing else. Just don't let earth switch. The last thing they need is more people to stack shields with. =_=