Bitcoin won't go back to $0 again 
Someone will buy bitcoin even the price less than $1
If you can shut down internet or electricity permanently, it would make bitcoin price go down to $0
Nah, solve blocks by hand, post results by carrier pigeon. Satoshi planned for this eventuality. Someone will buy bitcoin even the price less than $1
If you can shut down internet or electricity permanently, it would make bitcoin price go down to $0
not to mention that it would shut down many other thing and not only bitcoin , also i doubt bitcoin at zero would be your primarely concern without electricity and internet...
the great thing about bitcoin is that, in the case that bitcoin go to zero again, it can always restart from there and build another rally, basically immortal...