I agree that pronouns can be useful. I don't care about the gender of my fellow players - but I might need to use a pronoun for them. Pronoun is the correct question, not gender. I also want to maintain the data where supplied but go forward.
How about this?
If people have given a gender we automatically translate that to a pronoun pair (and just don't show anything if they haven't provided a gender).
e.g.
Change the settings page to lose gender but have a text box for pronouns (defaulting for people who previously supplied a gender).
If you fill in the pronouns then we'll use that (obviously)