Haha, thank you very much for the kind words, and for your highly detailed request! My answer has a short version and a long version, so buckle up ;)
Short version: "Uggggghhhhhh... probably."
Long version: I'm an idiot. Wait, no, that's also short. Damnit.
Okay, so I'm a solo dev and this is my first actual game. A lot of what I do is either "throw a lot of stuff at the wall and see what sticks" or "oh, this could be cool, I wonder if..." or "oh, I have a great idea for..."
Which is how the game has ended up with 17 main girls, 20+ side girls and over 30 one-shots. Which is too many girls, frankly, and a major reason why Act Two stalled out for so long - too much content to create for each character!
So I resolved to not add any more new characters to the game. And then I did it anyway. See "I'm an idiot" above.
I still have a lot of ideas for characters that I want to explore, though, and some requests that I'd love to be able to satisfy as well. And there are certain story beats and mechanics coming in Act Three that require new girls to be added.
Some ideas I've had, or been requested, that may or may not make it into the game:
1. Robot Girl (yes, this has been requested before and like you say it offers a unique perspective which would be fascinating to explore)
2. Doll girl (functionally the same as a Robot Girl, but magical rather than scientific)
3. Dragon Girl (it's a largely fantasy-themed game! Where are the dragons!?)
4. Slime Girl (same as Dragon Girl. Slimes! C'mon!)
5. Magical Girl(s) (because corrupting a team of magical girls sounds like fun)
6. Org/Fey/Edlritch warriors (this one almost certainly will make it in)
To name but a few off the top of my head.
So, yes, it's practically guaranteed that new girls will be added. And the thought makes me very, very tired ;)