I think at this point it's quite clear they are not ever going to do that. They actually stopped publishing their client source code and they aren't responding to any questions about that.
> Definitely, updated source codes will be online later today.
And the Desktop client[1] is kept very up to date. My biggest complaint is that they have stopped updating the API documentation [2] which has lead me to become a rather lukewarm telegram developer (though I still have a few projects I am work with)
[1] https://github.com/telegramdesktop/tdesktop [2] https://core.telegram.org/#updates-log