If it's not called a 4G, it will be called a 5, simply because 5 follows 4..........well, fancy that. IMHO, all those that argue strongly that it will be iPhone 6 are in for a wheelbarrow full of fail and should open a thread entitled "all those that called it iPhone 6 post here" so that it is easy to identify and ridicule them.
I am very happy to inform you that Apple will never use the number 4 and the letter G next to each other for a phone name. 4G is a misused term at best right now. And LTE isn't understood by the masses yet.
And it will be called the iPhone 5. Especially if they get the A6 up to production speed OR they go to a larger screen size.