The way I look at it is this - the Maya were on to something - history repeats itself (maybe or maybe not in precise mathematical cycles - they were the Ancient Greeks of their day in that to some extent). It does seem there are similarities to the world in the 1930s - mostly Xenophobia, and a feeling of pursecution. Only this time, it's on both sides of the fence. Europe, and other countries of the world have problems, or perceived problems with immigration (US, Russia, England, France, Germany - mainly the big players). With the Muslim population increasing in Europe, and exerting their cultural pressure, I wouldn't be surprised if there were an ethno-religious war around the corner in maybe a generation or two.
There already are issues occuring --
Europe's population is declining - in 20 years, many of this generation won't be able to have children because they're simply too old. With an increasing Muslim (and general immigration) population, this fuels xenophobic feelings across Europe (and the world). It's a feeling of "opression" (atleast a perceived view) on the European side. When laws start to change, people may start to protest, then riot over their way of life changing.
Minority feeling opressed (people and/or countries). On the flip side of the coin, you have the Muslim population who are crying oppression, whether it's happening or not. Some Middle Eastern countries could very well develop nukes, and any such super-weapon would make any nation feel bold. Egypt, Saudi Arabia, etc. have even been mentioned to consider developing nukes if Iran does.
China. I've read a few reports of Chinese men raiding other villages to find wives. In fact, 12+ years ago, this was a topic in my highschool Social Studies class when China started the 1-child policy. The main point was that they could wind up causing wars (wether intentional, or simply by international incidents) when men, or soldiers start raiding to seek 'wives'.
Then there's dwindling resources. Several papers have been written on "Water Wars" (I'm not sure if wars will be fought over water just yet, though). But, with China being the late runner into the Industrial Game, they're gonna be using up many resources that Europe, US and Russia once used. Maybe even Brazil and India will wind up doing the same. Especially with the US, China and India using up tons of resources, they may effectively strip the earth bare. Economies would blow up, which in turn usually leads to riots and revolutions (due to bad living conditions, and people overturning the establishment to try and make something better). There was an article somewhere that said we would now need 2 Earths to sufficiently supply resources for every nation. Demand exceeding Supply. (I'm not an economists, but I think that leads to inflation).
If any nation starts to "give in" to the extent that it affects life for everyone, then I think different groups would bound to be springing up to try and reverse the trend.