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It is really possible that all Bitcoins will be lost most specially if nuclear war will happen, the much more devastating EMP wars, the solar flare situation becomes worst or an asteriod will hit our planet because yeah we'll never know. And with that situation I think it will surely be lost forever. If Bitcoin is all mined, maybe price will go high or low depending on the situation.
You've answered the second question well - I agree with some of the statements, but you haven't answered the first question correctly. If all bitcoin are mined – then miners will likely not get rewards from each block as before, but they will only earn bitcoin from user transaction fees. That's what's happening if I understand it correctly - but the price of bitcoin likely won't fluctuate as much as it does now.