Obviously that's easier to implement if you don't have a written liturgy and the person speaking can just say whatever they want.
Eh, plenty of pastors and such play around with the "established liturgy" willy-nilly. One of the pastors at my East Lansing church usually substituted "She" for "He" or found a gender-neutral term even when it was printed otherwise.
I predict Bible translations in 100 years or so will be using "They"/"Them", because, as pointed out, it's mostly viewed as an accidental holdover, and God definitely appears using feminine imagery as well as masculine imagery in older texts. Now that English is getting a third-person singular animate pronoun, we'll be able to replace "He"
