I think Bitcoin mining reward will continue past 2140 I believe human will want lower and lower denominations of Bitcoin past 100 millionth fraction called a sat we are all use to for both the main chain and the lighting network.
Discussion
The two things aren’t linked. We can split satoshis over the lightning network already.
There will only ever be 2.1 quadrillion satoshis.
Am not talking about splitting am talking about adding more zeros it doesn't change the max supply it makes sure Sats doesn't become too unobtainable in the far future