Hypothetical question

not complaining, just saying that the OP seemed to pose that the blockchain itself is lost, meaning that the wallets lost the db, including backups. While this is highly unlikely as there are backups, as people have said, and hard wallets on USB's and such, the OP asked what appears to be a educational question.

the method of the crash would be important, or really the method of how these machines return to service. the whole system would recover, but if every wallet, every wallet.dat file and every copy of the chain was gone, then yes, that data is gone and the coins were just data, they are gone. i was going to say that mining would be near impossible until the next difficulty change, but that would be false too as the difficulty is contained in the data. So, it would be the new beginning of bitcoin, with thousands of wallets, instead of the two or three that Satoshi played with in the beginning. people everywhere would get popped with full 50 BTC rewards and that would continue until 2016 blocks had been mined and then the difficulty would skyrocket. the coins would lose their value on the exchanges, just like if someone dumped billions and billions of dollars in FIAT into the streets, it would become meaningless. But, the interesting thing would be if everything was lost, save for one copy of the chain. it would be neat to see whether that one machine could propagate its chain versus the thousands of others starting at 0/1