I dont think ada is similar to mia in any capacity. Ada never helped bioterrorists during bow development in the same way mia did. All ada did was steal samples and send them to other organizations but that's not the same thing as helping bow development. I dont like how some blame wesker's and simmons' crimes on ada at all. Wesker utilized his samples all by himself and she didnt even send g sample to simmons, he acquired g through sherry due to her infection in raccoon. Same thing with damnation where she kept special plaga sample to herself without sending it to simmons after figuring out his identity. Ada also didnt turn into a monster and attack leon in the same way mia became one and attacked ethan. Even carla didnt attack leon like that, she simply sends her explosive drones against all rather than only targetting leon. I cant believe ı've seen some blaming simmons' crimes on ada, other protagonists and even carla before calling re6's story stupid; it's extremely disgusting to see.I don’t even care enough about her honestly to even consider her in a chronicles spin-off or RE9. Mia reminds me of Ada in some ways with how shady and morally confused they both are. Shadows of Rose will be the end and hopefully we can move past the mold and back to viruses and parasites again.
But anyway if they want to conclude winters; ı guess they should conclude mia by making her the main antagonist of rose's dlc. Revillage doesnt do her justice, she isnt even playable unlike re7. It feels like a re4 situation where ada wasnt playable in leon's story in favor of ashley but she receives her own scenario with the next ports instead. Re6 has the best story and character development in the series imo and an important reason for that is due to the game's story revolving around ada much more than before. It adds to her mystery and gives her a good reason to not use her alias anymore. She's developed very well in the game while being portrayed much more heroic than her past appearances.
Idk what they will feature next but it will probably another " grounded " origin species like mold and cadou due to wesker's simulation. I dont think they will feature a virus that's part of progenitor family. Re6 concludes progenitor due to giving g and t-veronica the development they deserve. Plaga has more chance to appear but it might be a vendetta situation.