I speculate that if satoshi is alive he/she values privacy and has little need for large sums of money. Therefore the coins may sit idle for many years before being used.
IF it gets spent at all... I don't believe he/she will, but then again who knows. I believe that it is a very bad thing if a currencies ecosystem will essentially collapse if Satoshi were to start spending his coins at all, in speculation that Satoshi himself doesn't believe bitcoins are worth it anymore... Like what americanpegasus pointed out earlier in the thread.