If you compare BTC transaction with visa or mastrercard, it is still not enough, but with lightning network it will all change.
it will change but not drastically
while lightning network will increase the number of transactions per second, it won't get anywhere near
the numbers visa or mastercard manage , plus , as it was mentioned above, banks take care of mortages, loans etc. , not only transactions
bitcoin can't substitute the banking system just now but this is the goal to achieve in the future and LN is just the first step towards it
some interesting read about LN , the author is a sceptic, but it is an interesting read nevertheless:
https://medium.com/@jonaldfyookball/mathematical-proof-that-the-lightning-network-cannot-be-a-decentralized-bitcoin-scaling-solution-1b8147650800