I think the likely result would be more war. It wouldn't be with america, but without anerica providing protection to its allies in the region, the various countries in the region would probably be emboldened to fight it out themselves (im assuming in this scenario that russia and other great powers are also incapable of force projection. Obviously russia is busy right now, but historically they were knee deep in the middle east and much of us involvement now is a legacy of the cold war)