the right answer for the prom example is technically, "what is he wearing?".
Umm no? There's no "masculine preferred", also style guides are not "the English language", they're usage guides for the language; "What is she wearing?" is perfectly correct if they happen to be a female queen.
As to style guides, here's part of the 2006 version of the AP guide mentioned:
transgender Use the pronoun preferred by the individuals who have acquired the physical characteristics of the opposite sex or present themselves in a way that does not correspond with their sex at birth.
If that preference is not expressed, use the pronoun consistent with the way the individuals live publicly.
So you either get told he or she, or pick one based on how they "live publicly", which doesn't work for everyone.
But now, from a WaPo memo:
It is usually possible, and preferable, to recast sentences as plural to avoid both the sexist and antiquated universal default to male pronouns and the awkward use of he or she, him or her and the like: All students must complete their homework, not Each student must complete his or her homework.
When such a rewrite is impossible or hopelessly awkward, however, what is known as “the singular they” is permissible: Everyone has their own opinion about the traditional grammar rule. The singular they is also useful in references to people who identify as neither male nor female.
What we really don't need is a "new series of words", what we need is people who are a vanishing proportion of the population to get proportional attention. Now, that's not to say if they're a friend or a colleague you can't learn their pronouns as a courtesy, but to suggest everyone everywhere at all times needs to stop and ask what your pronouns are is too much effort and just feeds the ego of people who insist on such accommodations being made.
You may disagree, in which case I would like you to henceforth refer to me as "Lord Zaelath, first of Zher name".