Due to the tendency of bitcoin mining to trend toward a net profit of zero, in the future people mining solely for the profit margin will all drop out of the mining business, and mining will be done by people who have other reasons to mine. Such as large businesses who use bitcoin for transactions, and want to see those transactions processed securely and quickly. The only people making money off mining will be the people who sell mining contracts, the mining contract will be bought so the large company does not have to delve into the world of mining, they will not have an expectation of making back their investment, it is an expense to keep the bitcoin system running.
Although individual mining nor pool mining will likely never competely cease, most of the mining in the future is likely to be the above example or similar examples. A brick-n-mortar bank in a city that issues banknotes backed by bitcoins would not really need much of a safe, but would have a vested interest in mining both to help support the security of the system that they depend upon, but also to ensure timely processing of clients' transactions. Such banks would likely form receprocity agreements to process the free transactions of other banks' customers, as well as advertise their median hashing power to attract customers. Also, mining need not be looked on as a primary profit goal. ICeland could become teh bitcoin mining capital of the world, simply becasue they have high levels of geothermal eletric capacity and need the heat. Banks in the hot places of the world could simply contract with building management companies in ICeland and Siberia to mine in their favor, and the building uses the waste heat.