My thinking for a while has been that humanity is approaching a milestone... a bad one... a day when there will be virtually *NO* jobs available. I think it's going to happen in the next thirty years.
That means everyone will be on welfare, with government getting the money directly from corporations. Some time after that - and I'm not going to hazard a guess as to when - the corporations being taxed will decide that they don't need the government anymore and be in a position to pretty well defend themselves from it. The population will then starve.
I'd say that this is an argument for buying farmable land - except that corporations powerful enough to have no fear of government retribution will also be able to take the resources they want, including privately owned land.