I guess 50 yrs is too dire. However IMO the direst predictions you refer to are probably assuming a continuation of the current levels of resource consumption/

I guess 50 yrs is too dire. However IMO the direst predictions you refer to are probably assuming a continuation of the current levels of resource consumption/ecosystem destruction. But IMO it's far more likely that resource consumption in all its forms will keep increasing at a breakneck pace with every technological advance - thus accelerating the march to uninhabitability.