if no one spends bitcoin maybe altcoins will be gone, but chances of that happening is very small, remember bitcoin is cryptocurrency a great for the future
Altcoin will gone and bitcoin will die, as such no one is spending money, I think it imposible, bitcoin created not to be stored but used for the transactions.
Chances are really small today that bitcoin will disappear cause of nobody will use it. Today popularity of bitcoin is only growing. Soon governments and banks will admit bitcoin and will start to work with it. But some big hacking can destroy everything and bitcoin will loose it's users.
This is all just too simple, some bg hack wouldn't destroy Bitcoin, we already survived Mt. Gox and other big hacks, so I don't think a big hack would be able to completely destroy Bitcoin.
And about governments and banks working with Bitcoin: I don't think that will ever happen, they're too much invested into being in control of their currency, so they wouldn't want anything to do with Bitcoin itself.
Blockchain =/= Bitcoin