This is a question I have been puzzling over for a long time now. To answer this, we have to take a look at the current fiat system and how it functions; The value of fiat is determined by the countries economic strength and policies which affect supply and inflation, it is also heavily influenced by demand and supply on currency trades. It does not have any inherent value.

Bitcoin as a staple currency for buying goods and services would function in a similar manner, demand and supply would determine its value and at this point it would be much more stable than it is right now. But this is such a far away time that it would be difficult to determine how it would work from now.