Impossible bitcoin could be over because many investor keep trust with bitcoin, keep holding and waiting with bitcoin growing up to higher price, maybe bitcoin could be over when all country have banned bitcoin.
I guess bitcoin couldn't be over even the whole country banned it because i think some of the government already legalize it and i think sooner or later itll become a currency that a lots of people know and even invested on it. Lots of bignames also has been invested and been earning tons of bitcoin through mining so it's impossible to banned it.
And even all blocks has been mined by miners alt coins are living and still the supply and demand are balance.