I think BTC will thrive even
when the block reward hits zero. Transaction fees will be extremely high by then and BTC will be used mainly
for big transactions. Expressed in $ fees will likely be a multiple of the fees today, but as a percentage of the
BTC price they will still be pretty cheap.
Exactly this.
It won't matter to most casual users how many $ a main chain transaction is when things are scaled up. By that time, Lightning Network will be running even micro streaming most daily small value transactions for very small Satoshi and even sub-Satoshi fees. Transactions need to be layered and settled to the main chain. It doesn't matter how many MB or GB your block is, the need for payment channel layering is inevitable once you scale up, and once you have that layer, the fee for settling on the main chain will reflect its value. It needs to, because that's the way the value is secured from attack.