Maybe Blade won't, unless we learn more about that cast?
True.
I've heard rumours that Blade might introduce Elsa Bloodstone but it seemed she'd be a minor character in there.
I think it may just be that all movies with release dates will be sequels for established characters (and F4 is a team that includes a woman). Shang-Chi didn't really treat Katy or Xialing as proper main character superheroes either, so I guess with Blade being the next solo introduction movie that may be why. And I guess we don't really know if there will be in Captain America 4 or Deadpool 3 either. So I guess there could just be a solo female superhero movie again after that in the vein of Shang-Chi or Blade. Though I'm not sure which character they'd likely give a solo movie next.
Out of Wanda, Monica, Agatha, Sylvie, Katy, Xialing, Sersi, Sprite, Thena, Makkari, Kate Bishop, Echo, She-Hulk, Kamala, America Chavez, Valkyrie, Okoye, Nakia, Ayo, Carol, Gamora, Mantis, Nebula, Riri, Hope, Janet, Cassie Lang and Sue Storm none seem like they'd likely get a solo movie any time soon. They're all used as part of an ensemble, supporting role or on Disney+ shows. As for new characters I'd say Spider-Woman could be a good choice but it seems Sony has that on lock. I can't really think of other logical choices for new characters to get a solo in phase 4 or 5. I guess Shuri, Jane Foster and Yelena getting subsequent BP, Thor or BW movies respectively might be the most likely?