You are saying bitcoin can reach $500,000, as the snapchat investor said, that's 12 years from now according to his prediction.
So you are saying that in 12 years fees still will not be high enough to sell?
Who is the idiot that is going to sell before $500,000 regardless how prohibitive fees are?
Just my opinion, the most financially valid fee structure is the one where it is based on certain % of the transaction value involved.
For example, if transaction is $1,000, the fee will be $1.
And if transaction is $1,000,000, the fee will be $1,000.
0.1% in both cases.
Of course there will be a floor, like minimum fee per transaction, but it should not be outrageous, like minimum fee of $100.
Even then, the price of bitcoin per unit should commensurate with the fee charged.
If the minimum fee is $100, then the price of bitcoin should be $100,000, or something like that.
And that minimum fee of $100 will prompt people to spend in big amount.
Just my opinion.