Ironically, with “they” becoming a more common specific-individual-identity-pronoun preference, it is at risk of losing its inclusivity, and of becoming as problematic for unknown individual preference as she and he.

But that's a problem for the future, right now “they” is usually the best inclusive pronoun available.

I've also personally never understood the slash syntax. Since one word requires the "s" and the other doesn't, shouldn't we use parentheses like when words may or may not be plural? e.g. "(s)he" like you might say "socket(s)" or "Unix(es)"?

Moot point if it doesn't solve the issue of it still being binary, I guess.

Agreed.

I've been retraining myself to default to singular they. https://en.wikipedia.org/wiki/Singular_they

Old dog, new tricks. But I'm slowly adapting.