500K USD is going to be an EPIC! I'm keeping my coins on my wallet incase this will start going up to just 100K, i'd be very much grateful to who ever pump it. It might just be worth keeping BTC than investing to some ERC token which we thought would be huge like ETH.
This is impossible theoretically. Can you imagine market cap of all them when 500K USD turned real. This can't occur. Maybe it can be 50K USD in 20 years, but not 500K USD
Well, it all depends
And market cap as such is markedly irrelevant here as it is a purely abstract concept or thing which doesn't involve real money (read, it can be insanely high with no implications), so you can safely forget about it. But price itself, taken on its own, without volume is pretty meaningless too. For example, you can sell 1 satoshi for 1 dollar, and that would give you a price tag of 100M dollars per bitcoin. Technically, it will still be a legit price quote any way you look at it, but how relevant will it be without real volume? Maybe, this is what McAfee had in mind when he promised to eat his dick, i.e. he will simply sell someone a couple satoshi for a few bucks and thus will come unscathed