I don't think a young uber-kawaii female lead would work. But they could pull a new Shuki at us, and have an older woman play the female Rider.
Then the boys will have more of a mother-figure to look up to, and if they get a supporting cast of some guys they can relate to, then I think it could work.
The problem is that we have seen very few female Riders who were actually "normal" Riders.
When Toei gives us a female Rider, they always have to put the feminine level to the extreme in terms of suit designs.
Extra tight suits, high heels, boob-armor etc.
Put a woman in a male-Rider suit and you will hardly notice that it is a woman (especially since most suit actors are guys anyway)