No, the right wing isn't rising on Medium. There will always be quite a few, but I think I can safely say they'll never come close to providing half the content on Medium.

Why? Because of their ongoing war on education. Trump's strongest base was white men with no more than a high school education. As far as I can tell, those without at least some college often have less-than-stellar writing skills.

It's no accident that the higher the educational level of discourse on sites such as Medium, the more liberal those sites tend to be.