That is a very good point to discus.
I agree that volatility of bitcoin is a very important concern. The beauty of bitcoin lightning is the three points above, but the price changes are problematic. Strike Bitcoin solves this beautifully by changing dollars to bitcoin for the money transfer and bitcoin back to dollars at the other end. Because bitcoin exchanges exist in almost every country, bitcoin dollar-pairs or bitcoin -other fiat pairs exist, so this conversion is universally available. Plus the dollar is nearly universally acceptible.

Stablecoins are also an important point to discus.
I agree that stablecoins are competition for bitcoin in the money transfer business and point of sale transactions. Only the future will show if they are successful in displacing bitcoin. History shows that a first mover advantage is hard to overcome.So if lightning nodes facilitate this dollar transition they will help bitcoin succeed.
The problem there may be regulations for the lightning node operators to perform this bitcoin to dollar conversion, such as the requirement for a money transmitter license. In the US you need one for every state, while in other places you need just one, for the country you operate in. So unless the customer conducts the conversion, the laws and regulations limit the number of operators who can provide this service.

But laws and regulations can change, or processes can be made easier. So as we say here in the US, we have to wait and see what happens!
Thanks for commenting.