You really think a 4 inch screen is going to fly for the next 3.5 years?
The market want's larger screens. If Apple refuses to adapt they will be left behind.
I guarantee, we will see a larger iPhone in 2014. Maybe even this year still, but doubtful. I still think we'll just see an iPhone 5S in Summer / Fall, using same exact form factor as the current iPhone 5, just upgraded hardware. And that iOS7 will be the big deal this year, a revamped UI being the big change.
And then in 2014, we will see an all new phone design and shape, with a 4.3" screen.
But just maybe, we will see the 4.3" iPhone this year, but can't see really that happening, with Apple just releasing a whole new design just last October, they typically seem to stay with a new design for two years. I bet the iPhone 6 in 2014 will be the big update.
In 2014 all Android phones will be around 5" screen size. So even a 4.3" increase in iPhone screen size will seem small, but in my opinion the perfect size for a phone.