That the world can not be sustailned

I fundamentally believe that although humanity appears to have an exponential growth rate of demand for anything and everything that this trend is curving off. We see that consumption of non-renewables appears to rise year on year yet we see that many nations now are investing in alternative sources of energy. The high demand for these resources and their increased consumption is only there because of their economical attractiveness, these resources loose this advantage when their supply runs low, then alternatives come into play. For example the amount of coal and gas used in power generation will never fully diminish because it will hit a certain point that the unitary cost is higher than of renewable alternatives. We may see this in daily essentials like food for example. Meat requires a larger amount of calories to produce than it gives out when eaten, when demand rises way above the supply capacity to give out calories the price of meat will rise above the point that it is more attractive than say wheat or other foodstuffs that are less attractive to meat consumers. The essential economics of it will force humanity to disregard tastes and look to more utilitarian means. If we move on to a more extreme case where even at peak production of all essential goods and services we cannot sustain the basic demands of humans then what do we do? Well we can look to Malthus to tell us that if we reach this point human natural checks and balances will reduce the population so that demand for the natural capacity of supply is at a level where it is sustainable. We can increasingly see that we are getting closer to 'post-scarcity' where we have enough supply to have everything for free, no human input would be needed in the production line after the initial building. We see this in a few sectors at the moment such as media, with music games and books being able to be infinitely re-produced for free. If we look at a resource that is already becoming scarce in many parts of the world that is essential to survival, water, we can see that humanity is already coming up with checks and balances. So called 'water wars' already tell of humans killing each other off without nature having to intervene. Furthermore it appears impossible to actually 'run out' of natural resources that we depend on for survival, the original point given was very very broad on what resources, the 'worlds resources' will never run out if we talk of natural resources like soil space and water as the demand relies on the supply. If we ascribe an arbitrary value to demand for water (1000) and an arbitrary value to supply (900) we can postulate what will happen. Demand exceeds supply by 100 units, the market will compete and drive up the price of water so it becomes economically unattractive for some (they cannot afford it). Obviously this is not going to happen, people need water. People will fight over it eventually and kill each other off, this reduces demand to say 950, after this effect lack of water may kill off those who cannot get to any of the supply until the demand falls to a level where the supply is sustainable say 500. If demand sits at 450 the system is sustainable, drinkable water is in great quantity compared to demand and even if some is contaminated there is still plenty. We also know if water supply runs low humans will use their greatest adaptation to survive, their brains. Humans have come up with scientific solutions for many problems and we now live in the developed world to three times the age we would naturally. Overall I state that resources will become economically unattractive and alternatives will be used, humans will go past their tastes and become utilitarian before dying out, checks and balances will effect the demand before the supply and finally humans will innovate. (I haven't really done a debate before so I hope this was okay :) )