Could 1 Satoshi (SAT) be worth $1 one day?
It's possible, which means it happened either because,
1. Bitcoin is widely adopted
2. US dollar suffer from big inflation
3. Global financial crisis happened
3. Combination of above possibility
If that happens and usd is still worth anything, on chain transactions are going to be very expensive (1 dolar per byte, minimum fee)
Lightning and off chain transactions are going to be really needed, and on chain transactions are going to probably be used just by banks and whales.
Bitcoin fee minimum fee is 0, it's just default acceptable transaction fee is 1000 sat/kB. We could reduce it to 1 sat/kB (or even lower) and allow smaller fraction (e.g. mili satoshi) on Bitcoin network.
Afaik sub satoshi doesn't exist in the blockchain, and less than 1 sat/vbyte transactions do not get broadcasted
It would take big code changes to make subsatoshi happen, isnt it? But 1 sat/vkb could be a nice solution and maybe not that hard to implement. But I think off chain solutions are going to be the thing in the future... like hal suggested
I believe this will be the ultimate fate of Bitcoin, to be the "high-powered money" that serves as a reserve currency for banks that issue their own digital cash. Most Bitcoin transactions will occur between banks, to settle net transfers. Bitcoin transactions by private individuals will be as rare as... well, as Bitcoin based purchases are today.