They're just interested in a different variety. In the US, one in five people is black. In Japan, 97% of the population are Japanese, and the most numerous minorities are Chinese and Koreans. At the same time, it is impossible not to notice that tokusatsu is also becoming more diverse, for example, more and more women and actors over thirty appear in the shows, because this make sence for a country of centenarians with a predominantly female population (though not as much as in my homeland). So my point is that in the era of Reiwa, we will definitely get a female main rider, but I am sure that she will not be Gotchard.
P.S. And in spite of my predictions, Toei will decide to start next era with the first female main rider.

Ehhhhhhhhhhhh the main char being a female I don't see it happening, now the secondary sure

Kamen rider is meant to bring in young boys so a female main char wouldn't do well

A lot of boys watch anime about magical girls. One can hardly ignore what a hit Sailor Moon was in the 90s. Plus, in Kakurengers and Donbrothers, the main characters are girls and the reviews for these shows are good. Also, if the maximum similarity with the main character was so important for the audience, then the child heroes in tokusatsu would not be so hated. If a boy can associate himself with a ninja turtle, then he can with a girl. In addition, society is changing faster every day and it is not known how much more friendly the audience will become in the future.

Regardless of who's the protagonist though, Ninja Red and Don Momotarou are still the faces of their respective teams, whereas a female Primary Rider would have to be the face, unless she's equivalent to Riderman. The protagonist can be any gender or race you want, but for marketing in this genre, the face is pretty much going to be a Japanese dude.

We'll have to see how Cosmic Fury handles Amelia as the new red ranger. Even though she's likely still SIC to Zayto, it's a big step nonetheless that could potentially encourage Toei to follow if the risk pays off. I definitely think Sentai has more options than Rider to try something like this.

That's why I'm talking about the future. The world is changing, the audience is changing, tastes are changing, and toys need to be sold. Sentai can do it sooner, but the rider will obviously cause a bigger splash. Plus, if Toei approved of such nonsense as the main rider without a bike (hello, Shinosuke!), then the female lead also has a chance.

I remember when Kinoshita suggested a female lead Rider for Revice he was immediately told no (and thus Jeanne was born).

We'll probably get a female Rider, I guess it's just a matter of how many we get from the start since most recent shows have been unloading Riders in the first quarter.

Kinoshita was a rookie who didn't have a particularly good debut in the franchise. The question is, would Toei be denied if Inoue approached them with the same idea?

I think it will happen here too, but I hope that, unlike Geats, Gotchard at least does not have to share the pilot episode with anyone.

If it’s a card game theme, can you all imagine the main rider’s rival rider like Seto Kaiba?

Exactly. If they're ever going to do a female Primary Rider, of course they need to do it right, so they can't just let any writer do it cause they asked to. I certainly wouldn't trust Kinoshita with this concept after seeing how much he neglected characters he clearly didn't care about and I think Toei made the right call vetoing him. But someone like Inoue, or Komura, now they could probably do it in a way that would satisfy people.

I bet it'll be more like Kalin from 5Ds