I never thought much about the effect of permanent loss on Bitcoin. Unlike cash, encrypted wallets and the block chain make theft harder than just destruction of the money.
A virus which deletes wallets instead of trying to exfiltrate BTC seems much easier to implement and would be pretty devastating for the currency.
Damaging but not fatal. Bitcoins are divisible down to 8 decimal places so the value would just scale up according to the reduced supply. And 8 decimal places is a software limit; a revised protocol could increase that.
Sounds like bitcoin requires a backup system by default, then. Because otherwise, the first virus written by some pissy kid that just deletes wallets will devastate a lot of people.
A virus which deletes wallets instead of trying to exfiltrate BTC seems much easier to implement and would be pretty devastating for the currency.