I am linking to this post for reference.
The acceptability of "they" as a singular pronoun is growing. Has it grown to the point where it is acceptable in formal publications, such as journal articles, business proposals, or political speeches?
It seems to be that it is not quite there; most people are still too concerned about being negatively judged for it. However, the options of "one", "he or she", and "s/he" are similarly avoided for their cumbersome and pedantic tones. I often see either "he" or "she" used exclusively as an alternative, however, as there is no official stance on one pronoun or the other referring to either or, this opens the door for issues of implicit gender discrimination.
I try my best to skirt the issue altogether when I write, often dramatically revising paragraph -- and even paper-- structure. This, of course, is ridiculous. What is the best option for communicating the very commonly needed genderless singular personal pronoun in formal situations?