please note, I am writing for my own skill improvement, and these are my opinions down there:
 we know Bitcoin mining rules allows for a deflationary force. and I am talking post US however it goes down, in a free market where what happens is an act of nature.

imagine, BTC now is nominated in %20 of world's market transactions.
after a parity with market growth and stability in BTC value, there will be no mechanics for the worldwide community, to study the heavy production growth in the free market and the pressure it causes.
this pressure in theory is bad, it goes against the natural growth and prosperity of the human race, it's what humans do, to create and expand, most of the time, this is what we do, it's bad because this natural growth needs money supply to account for it, it was synthasized, simply created of the miracle of life.
it's, for me, suffice to say, emerging cryptocurrencies that will solve this problem, the inflation problem, will foster and thus, BTC has delivered it's final objective, after helping in shifting wealth, it can be traded in an ever growing world, where it will gradually acount for less and less ratio of world's transactions, mainly because other currencies have grown in supply steadily. in the foreseen future BTC will retain it's value, in the growing world.