How will fragmentation affect the end user?

It depends how Apple do it, but hopefully it won't have too much of an impact.

I would assume that if a longer screen was introduced current games would play as they do today but with black bars at the side. Similar to how a widescreen video has black bars above and below it when watching it on an iPhone.

Going forward though, it may become an issue because if developers want their game on all iPhones they will need to support 2 screen sizes.

Apps like Facebook, eBay and RSS readers will probably take care of themselves because Apple's App enviroment is quiet good at that, but games will be different.

Pretend your a games developer: Do you spend extra time and money making your optimised for both screen sizes, do you just make it for the new bigger screens and save yourself time and money, or do you make it for the smaller screens letting you get on every single iPhone.

Obviously the last is the most appealing, you get the biggest market and you save time and money.

It's Apple's job to make sure this doesn't happen.

 

Infinit scrolling.

Problem solved.

 

If Apple really wanted to avoid fragmentation they could only approve app submissions that support both screen sizes...