I'm looking for a singular, gender-neutral pronoun that can be used when the speaker doesn't know or want to disclose a person's gender. For example, take this sentence:
He is coming with us.
I've looked for some alternatives on this question, but "they" gives the impression that multiple people are coming along:
They are coming with us.
"One" doesn't fit in this context, and I'd prefer to avoid using he/she if possible.
Is there a commonly used alternative to singular they?