What if the "peak oil extraction" has been already left behind and we find that more and more and more electricity is just too expensive? What would happen? ASICs would have to be more power efficient and many miners would be left behind. Mining companies could get too centralized and at one point be infiltrated by states? Even banksters could have a big share of many mining companies (like jpmorgan and similars now own a great slide of the world) and decide to perform constant 51% attacks.

Another issue. What would happen on a war economy. We have been living a long period without wars but that won't continue for long (i hope that is not true). On a war economy and under war laws states could exert extreme violence to anyone using bitcoin or entire regions of countries could just shutdown the internet like north korea or lybia during revolts. What would happen? many forks?

Other possibility. What happens with bitcoin when there is no internet, when 3G lines are switched off and there are not even mobile lines for failing infrastructures or in zones with inhibitors? What would happen with Bitcoin?

Just some thoughts