Will all the Bitcoins ever just disappear?
even if just 2 people were mining it, it will continue.
with that said there are already people that have permenant systems in place, not for the purpose of making money, but for the purpose of keeping an accurate copy of the ledger, decentralised.
Can the price drop very low to a dollar?
if all you care about is the $$ of bitcoin.. your missing the whole point of bitcoin.. but lets settle your mind
the price can go in any direction.
such as if only 2 people were mining it they would get1800 coins a day (if evenly split between 2) so if all they wanted to earn was $50 a day they would sell coins for 3cents each..
so its possible..
that being said, the cost of mining is in petahashes and equipment costs/electric costs and the splits of rewards will make it more expensive to mine at the continual rate. thus they wont sell coins too cheap as miners have to break even and thus the price will rise..
Will it go very, very high???
as explained in last statement..