Ncsoft has done that themselves
I haven't played classic in probably about a month or more now. I uninstalled it. I am playing on a P.server, but it took me a while to choose to do so.
With that being said, if the P.server I'm playing on shut down... I'd just move on. I have no interest in classic/retail Aion because of what it / ncosft is. Losing this P.server would not drive me back to classic, it would just push me on for good. Other people likely would follow that. Classic's population has always been abysmal, the only time it wasn't was around launch.
People can still cruise the forums, they can still "be interested", but it in no way is a "commitment". Many of us grew up on this MMO, many of us also just want to watch for confirmation that the game is crap, which we get. These forums are as dead as classic.
People leaving classic isn't just because there are P.servers around, it's because ncsoft is crap. I'd just move on to RDO/OW/Star Citizen/FF14/ESO.... like many other people would do.
Classic killed classic. Not anything else.