I know that nobody really knows, but do you have any guesses? I'm assuming they will soon be on their way out, given the direction the newest retina MBPs are taking. My MBP is just under three years old, but I'm tempted to grab a new 13" non-retina MBP (the only one left with an internal disc drive) while they're still around.
(Reasons if you're interested: They are cheaper; I don't like extra hardware cluttering my desk, i.e., an external drive; I like having an Ethernet port, which the retina versions do not have.) THANKS.
-Bob