we could divide it in second layers, allowing the bitcoin being subdivided to sit around on the blockchain

Further than 1 sat? I feel it's unnecessary

The lightning network already goes down to milisats, so that allows for plenty of increased divisibility already. These and other forms of divisibility on layer 2's will likely provide all of the divisibility Bitcoin ever needs

There's two parts to this really:

First - how and where:

On a layer above the base layer of Bitcoin - such as Lightning - divisibility beyond 1sat is already in place. Divisibility down to the milli-sat (1/1000th) is already part of that protocol.

On a layer above the second layers (like Lightning), additional divisibility could be implemented - think of further divisibility within a L3 such as Fedi/Cashu.

Now let's talk about why:

As more value is ascribed to Bitcoin, the fiat-equivalent pricing goes up. At $1m bitcoin, each satoshi is therefore worth 1cent. This means at $1m bitcoin, we have the same divisibility that we have today in the dollar system. All good.

But, as Laura knows, the accrual of value into Bitcoin won't stop there; in fact, it will accelerate. So further out (dollar system most likely long in the rear-view mirror), at $100m bitcoin, each satoshi is worth 1 dollar. Ignoring the aspects of purchasing power parity, at this time, further divisibility may be required .. and good news .. we already have that in Lightning.

Hope that helps your thinking

I don’t understand the use case. What is the smallest realistic fee? Maybe 200 sats. So why would you need to distinguish decimal if each move costs more than 200 units?