Different strokes different folks, not everyone who owns or wants an iphone uses its capabilities to the most, and this is evident with the fact that iphone 4 is still alive. Does it run the most demaning apps? No, is it a great phone? Yes. My friends dad who never owned a smartphone just got the 4 and he loves it. His next iphone will probably be the 6, but for now he is blown away by the 4
This model has worked great for 20+ year in pc industry, especially windows pc - they range from $300 to $5,000, why do you think it will fail on smartphones?