In my opinion Satoshi might still be alive and he might be slowly selling his coins backwards.
Basically if he sells the BTC that he mined in 2009, then its very easy to track him down and with all the wealth he possesses he might get tracked down, kidnapped, or even some governments might want to have a word with him.
He solo mined most of his coins in 2009, but how do we know if he didn't GPU mine some coins in 2010 with a mining pool which would of made the coins harder to link to him.
Plus we don't know his situation. He could already be a wealthy individual and he doesn't need anymore wealth.
When you got a $1 Billion US dollars, will another $1 Billion really improve your life? Its already more money that most people can spend in a life-time and why attempt and sell those early coins and get possibly tracked?
You need facts to back this up otherwise it is just baseless speculation. If satoshi was going to sell his coins then he almost certainly would have by now. He probably either purposely abandoned them for fairness, or he's dead. Maybe both. I think there's more chance of a supercomputer cracking his keys at some point than him actually coming back.