There is no question that the next iPhone will be the 5S and not the 6. The reason is because Apple wants to regain their huge profit margin amid investor worries of them shrinking. an iPhone 6 implies a new form factor. And that requires a revamped manufacturing process resulting in declining margins. Apple prefers to reuse the current form factor in order to spread the cost over a longer period. This is what they have done since the start. And it's effective. So don't bet on them changing the pattern.