Collectively "Satoshi Nakamoto" is waiting for mass acceptance before revealing himself and starts dumping coin in market.
He might never know when that stage is achieved. It might already have or might happen soon. Even if it is mass accepted, the price won't necessarily sky rocket.
Although if it is mass adopted, at suborbital price, then he can probably dump whenever and it won't twitch a penny.
Regardless of the price, in order for satoshi (or anyone for that matter) to be able to sell large amounts of bitcoin without affecting the price significantly, the market will need to be very liquid, and have a very high amount of trade volume. I agree that both a higher price and higher adoption rates will help improve liquidity, these two alone will not necessarily make it easier to "dump" large amounts of bitcoin on the market.
Regardless when satoshi decides to sell he will probably not do so all at once, rather would sell only a little at a time
a million coins would crash the price to zero ... no? \_(x*O)_/