I really have no idea what that would look and sound like. We have a neuter gender, but it's not really fitting to talk about people (like using "it" in English). I think we do need a new gender neutral suffix, yes, but I'm not qualified enough to make an attempt at devising one.

Or maybe we could just start using plural, like "they" in English. It would sound odd, but not as odd as a brand new type of ending.