After doing some more research, i have come to the conclusion that if we consider that all money will be spent at some time and that net change in spending should be near 0% after inflation etc. is taken into account (some people will spend when others save etc.)
Global expenditure was set at $23.42 trillion by the CIA
https://www.cia.gov/library/publications/the-world-factbook/geos/xx.htmlIf we consider that this value includes money which someone has saved in the past then we can say that this is all the money that bitcoins will need to cover because storing money in bitcoins at this stage will reap no benefits (at the stage when everyone uses bitcoins and its price has stabilised). That means that each bitcoin will be worth $1 million, however, businesses may push litecoins into the mainstream due to its faster verification in which case bitcoins may be worth significantly less.