To the best of my knowledge, and having heard Nacin say it explicitly, no deprecated function has ever been removed from WordPress to date.
No guarantees for the future, but it’s never happened yet. Still, avoid deprecated functions.
If you like this question & answer and want to contribute, then write your question & answer and email to freewebmentor[@]gmail.com. Your question and answer will appear on FreeWebMentor.com and help other developers.