Everything in our life, works in cyclic manner; one triggers other and the last one triggers again the first one. Dependency. One simple example, how gold gets its value or trees are causing more rain and rain supports growth of trees.
^ Definitely right, Satoshi has thought of this and informed us about the mining difficulty back then. There might some miners who will end or stop mining but rest assure there will still be miners who can afford mining despite the cost for the price will definitely go up. For 2136 definitely I am no longer alive by then but we cannot predict what will happen in the future either bitcoin will survive or bitcoin will fail which I really hope not and for now what I am holding on is that I can see progress in global acceptance for bitcoin.