Ah, the cool $1 million per Bitcoin in 2018. Let's see what this means.
If miners decide to sell all their mined Bitcoins, (or 50%), this is how much daily fresh money is needed on the exchanges for the price to be stable:
2014-2016 : $3.6 billion ($1.8 billion if 50% sold)
2017-2020: $1.8 billion ($0.9 billion)
2021-2024: $0.9 billion ($.45 billion)
etc.
So, if Bitcoin is $1 million in 2018, good luck in finding that daily one billion dollars. (0.3$ trillion in a year). Dr. Evil would be proud.
I too wonder about the consequences of what the log trendline suggests. If and when bitcoin prices reach $1 million in 2017 and top out, there should be 50% adoption by the population of speculators. By way of clarification I mean not full adoption by the underlying economy, rather of the people and institutions that will ever purchase bitcoin as a speculation, half of them will have done so by 2017.
In 2017 the block reward will be halved from the current 25 to 12.5. At the rate of 6 blocks solved per hour, the daily block reward totals 1800 bitcoin, thus requiring $1.8 billion to buy all mined coins at $1 million apiece.
Total daily retirement savings in the US is about .5 to 1 $billion according to the
Investment Company Institute. And given that only a fraction could reasonably allocated to Bitcoin, the majority of the daily required $1.8 billion will come from other sources including non-US retirement savings and especially I believe - merchant trade and the foreign exchange market.