Afaik the lightning network currently supports the 15th decimal place...
Cute, but unless
BTC is worth $10 million what does that realistically achieve? Where are you going to spend $0.0000000002?
Apps in Lightning for streaming data, and paying by the minute/3 minutes/5 minutes? Plus the macro-economics of Bitcoin does point it to a price-discovery to 6 digits, and maybe 7 digits.
Does that have a practical use case besides being a proof of concept?
It didn't stop Bitcoin from being developed. Here we are.