2) It must be clear that transaction costs using LN are much smaller than without it.
I believe it will be obviously clear.
The problem is that if fees continue to be very low, people will continue to think that this will be so forever, and not bother about LN. They could even refuse to open a LN channel because of the fear that opening and closing it could cost them even more fees (which is a fallacy, as for LN you typically pay fees 1 time for many transactions).
It appears that Bitfinex already allow their clients to make LN deposits to their accounts. Quite a big development really, it perhaps got mixed up with the news that Bitfinex were running a public LN node?
Thanks for the info, that's really good news and I wasn't aware of it. It
seems also to include withdrawals to LN (which is, imo, at most equally important than deposits, so people can buy directly LN coins)
and seems to have been added already in December 2019. The deposited coins are credited as "LNX" and can be converted for free to Bitcoin. It is true however that there are relatively few news articles about that and most of them focus on Bitfinex' LN node. Since September 2020 also Wumbo channels seems to be supported.
They also seem to want to add Tether deposits/withdrawals via LN. As Tether is an Omni token, this could mean
OmniBOLT support.