Originally Posted by HarryT
English has, on the whole, lost the distinction between the informal/formal singular/plural second person pronouns "thou" and "you" (although "thou/thee" is still alive and well in some English regional dialects, such as the part of the country where I live). The same could perhaps happen with third person pronouns, although I personally doubt it.
I don't expect he/she to disappear. I do expect "they" as a third singular third-person pronoun to become more accepted.