They are not going to increase the number of bitcoin in the circulation but without doing that we can still buy a cup of coffee using bitcoins. But that will only happen if the confirmation rate will be much faster than before and the miners fee will be lesser and reasonable. Anyway bitcoin is already a global currency since it can cross borders all around the world but it will never replace the fiat currency.
I like what OP said on that, here:
What about scalability doing many many fast-transactions/lightning network?
there are many options and none of them have to involve changing bitcoin. with fiat you have outside counterparties assigning responsibility for fast coffee transactions, i.e. Visa network or MasterCard network. Come up with a counterparty solution or let another coin become a credit-card or have a startup either become a trusted solution or develop a sidechain or some trustless solution.
Last i checked, its been clear that many of us around the world have been able to send/receive bitcoin with no issue - as so many of our friends have been doing in Japan, India, Russia, Greece, America, China, Nigeria, various South American countries, the UK. all around the world bitcoin transactions have been happening for already for years and are happening even as i type this.
scalability forced upon bitcoin would destroy bitcoins primary use of store of value.
hack.
They make very good points about bitcoin primarily being a holder of value with stability being a key element of that and lightning transactions being better suited to alt coins or 3rd party solutions.