It just seems incredibly unlikely at this point. They obviously lost a massive part of their market to smart phones. Nintendo lost a fair chunk too but have managed to hang on, I assume because of the strength of their first party games.
Then when you add the fact that the Vita works as a screen for the PS4, it seems unlikely they'll bother retiring it. I bet they'll just try and keep indies continue coming for the next 2 years or so, then it'll quietly be forgotten.