It's impossible to predict how bitcoin will grow. I believe bitcoin will grow on bubble-burst cycles with huge pumps, dumps and new floors.
Most people believe in 21 BTC being a good goal. Think in terms of total supply. 21 puts you in a limited group of 1 million (less, considering current supply + lost BTCs)
This should put you in a wealthy situation sooner or later. If you want $1.6mm.. then you'll need $71k per coin. It's probably realistic in 20 years.
Let's do some math. in 10 years almost all coins will be mined and at least 10% will be permanently lost or unusable (Satoshi's stash, lost keys and passwords) We'll be left with with maybe 18 something million in circulation. The population of Japan is 126 million, so there won't be enough coins to supply the Japanese, not to mention the rest of the world. When people realize that they'll buy out everything.