Transmission of the virus via paper/banknotes is unlikely, and completely impossible if you wash/disinfect your hands regularly. Should we also stop to read newspapers and books?
That's not quite the same. Handling cash where you can't wash your hands immediately after you touched notes/coins handed to you by someone else can be a risk, and it can add up if you do it a lot (e.g. you sell something in a market). Granted plastic cards aren't much better if people need to hand them over to the cashier and/or enter a pin.
I wrote
"completely impossible" which of course is not true if one does not adhere to the rules of frequent hand disinfection. Although it may seem quite difficult, but I personally disinfect my hands after every contact with banknotes, because such are the rules in every store, supermarket, hair salon - you can't go in or out without disinfecting your hands. Of course, we should always avoid touching our eyes, nose and mouth with hands that are not completely clean.
As long as the banking system hasn't failed (as it almost did in 2008), bitcoin isn't ever going to become a mainstream currency.
The complete collapse of the banking system is quite unrealistic for me, because the whole world economy is closely connected with banks, and also with the governments of the world. Proof of this is the fact that it was governments that rescued banks after the last recession, with taxpayers' money, of course. There is no doubt that the same thing will happen again if necessary, but only because most people accept such rules of the game. Most people don't really want more responsibility for their finances, if you give them a choice between a plastic bank card and a PIN vs Bitcoin and private keys, 99% of them will still choose this first option.