Can they mean it?

Dennis Baron (@DrGrammar on twitter) linked to a text from 1789 in which William Marshall writes about a gender-neutral pronoun in Gloucestershire, ou, meaning either he, she or it. It describes the word as being analogous with plural they. So ou will means he will, she will, or it will. In the same way, they will can refer to men, women, mixed groups, unknown genders, or inanimate objects (‘how are the trains? Oh, they will all be delayed’). This made me wonder about singular they, which can refer to a male or female referent (which would also be grammatical with he or she respectively), or someone of neither/another gender, or unknown gender, etc. But I’m pretty sure it can’t refer to something that would normally require it. I don’t know if I can think of a context where it’s not clear whether the referent is animate/human or not, therefore making a word that covers all possibilities a useful addition. Perhaps ‘Someone or something has knocked over the garden fence’, where it could be vandals or the wind? 

Incidentally, I’d saved the link to this with the note to myself ‘Can they mean it?’, as per the title of this post. I was so confused about who might mean what, until I realised that I was asking whether the word they can mean the same thing as the word it.