Can't see it personally. It's going to have to take some serious widespread adoption for something like this to happen.
$10k, no problem, $500k is dreamland.
Who would have said that the bitcoin would arrive at more than $ 2000 at its launch, we all also said "DreamLand".
The bitcoin will be increasingly scarce and the demand will only increase if it settles in and is recognized by countries (something that begins to happen) Except the world war, big stock market crash that will disrupt its market. I think the bitcoin is untouchable.
Of course, the big boys are coming to play but they'll just dump hell out of it when they hit their profit targets. If BTC was to hit $500k, from where we are now that'd be a 250x increase.
In the next 12-13 years, BTC is going to have even more competition from currencies that aren't out yet, don't forget that ZEC and ETH are the big coins at the minute and they're fairly new in comparison.
So although BTC is the #1 coin, I wouldn't be surprised if a BTC 2.0 came along in the form of an alt. Don't forget plenty here are kicking themselves for not buying at $1 and trying to board the next hype train.
I think what I'm trying to get at, is that BTC will continue to thrive in the future, with the emergence of new currencies BTCs marketcap will start to fall even more.