> I think 'they' as a gender-neutral pronoun is widely accepted in speech and may have greater acceptance in writing than once it had
Well, less than it had before the Victorian effort to forcibly re-engineer English in the image of Latin, but more than it had at the height of influence of that effort, whose influence is still waning.
> For me, that use of 'they' shall remain incorrect in writing (by virtue of introducing ambiguity relating to number)
The ambiguity of number ship pretty much sailed with “thou”.
Well, less than it had before the Victorian effort to forcibly re-engineer English in the image of Latin, but more than it had at the height of influence of that effort, whose influence is still waning.
> For me, that use of 'they' shall remain incorrect in writing (by virtue of introducing ambiguity relating to number)
The ambiguity of number ship pretty much sailed with “thou”.