Bitcoin has not been very old in the market. It will take many years for it to reach the limit and thinking of such hypothetical things is just a waste of time.
People are not very open to change and Bitcoin is a huge change for them. If they only less ignorant, they might be able to realize how the current system (banks) is over-abusing its position.
Yes, when Bitcoin mining will stop.
So even after mining stops, the price of Bitcoin will remain unstable? even if it depends on demand.
Why are you worried about events that will not occur within your lifetime? Nobody can give you a definite answer for that question.