I feel like nobody's done a really great 3d scifi soulslike. (There was that game where you use a power loader and cut opponents' limbs off or something? All I remember about it is that it was pretty mid.)

Modern horror. Maybe something akin to urban fantasy/horror. Soulslikes tend to be very horrific already; and survival horrors are only a few steps removed from soulslikes. Going a little more scripted and narrative would help a lot. And there are already a lot of great experiments with horror rpg's to draw inspiration, Like the fear and hunger series and don't look outside.

After Lies of P, I started imagining all sorts of retold old fairy tales and classic stories. Wizard of Oz (which I'm excited for), Hansel and Gretel, Arabian Nights, The Odyssey! There's so much potential.

Cosmic horror in a sci-fi setting.

It would be a great setting for a Bloodborne sequel, perhaps with a retro-future aesthetic like Alien.

A video game adaptation of the DS9 episode "Battle Lines".

Three musketeers....

What is this picture from?

Cutesy invasion. Like the invader-o's episode of Fairly Odd Parents. The juxtaposition between the gritty, git-gud attitude of the gameplay and the over-the-top kawaii characters would be incredibly engaging.

Plus, maybe we could get away from drab colors if we push hard for pastel

Maybe it's because of a recent discussion on here, maybe it's because of Mapocolops' recent Let's Play but I would love to see a twisted Alice In Wonderland Soulslike.

Any decent game with thoughtful references to a certain non-mainstream culture

Elden Ring's mom's butthole.