I agree: bitcoin won't replace cash.
I think it is strange when people oppose bitcoin to cash.

Some crypto may replace cards, but not now.
Usually cards not operate with real money, they use some "virtual" and balance draw up only at the end of banking day...

My standpoint is that crypto (not especially bitcoin) can replace SWIFT.
SWIFT is slow and weak.
Nowdays needs fast and protected money.

My minds about crypto:
https://steemit.com/blockchain/@soomrack/bitcoin-blockchain-steem-middlesociety-and-math-management