I'd love to see a Liberators movie. I personally prefer "Liberators" to "A-Force" but that's just me.
Valkyrie
Captain Marvel
Gamora
Nebula
Mantis
Wasp
Rescue
As most of these characters are Cosmic, particularly the ones who would probably be interested in signing on for this film (i.e. not Paltrow) they will most likely go up against a cosmic threat. In my opinion a vastly untapped potential antagonist would be these smarmy spoiled patriarchal figures:
Beyond just both sitting gathering dust so to speak in the MCU, the two have also never interacted. It would be a lot of fun to see the Liberators attempt to Liberate Sakaar and Knowhere from these two men's weirdly oppressive rule.