The title seems unthinkable, but for all we know the new iPhone 6 may indeed by the first Apple phablet device that could compete with Android devices such as Xperia Z1 Ultra, Galaxy Note 3 and the Oppo N1. The fact on the matter is that this is a very popular market right now and Apple has done absolutely nothing to get their share of the profit. However, how would the creating of a large 5.5 inch iPhone be accepted by current iPhone users? While a lot of people complained about the treansition from 3.5 inch displays to 4.0 inch that did not stop sales for skyrocketing. However, this seems like a much more radical change in planning and therefor it is unlikely that Apple won't have a separate flagship for their current userbase that enjoys smaller screens.
Adopting the Samsung Galaxy Concepts?
In my personal opinion this idea wouldn't be half bad - create a main flagship model and a larger phablet device. You see other companies that use Android doing this all the time and the best example is Samsung. Sure, their Note 3 is now a name of its own, but it all started as a spin off from the Galaxy S license as this was the most popular, top-selling and most loved series that Samsung had at that time.
So, how about a iPhone 6 that won't exceed the 4.5 inch size and a iPhone 6X or something which would be a phablet? I don't know about the rest of you, but that sounds like a brilliant idea to me and I think it to be fair towards everyone's needs and requirements.
As always the Internet is loaded with rumors and speculations about the new upcoming device and most of them come from people who don't know much about the industry to begin with. Nonetheless there are a lot of interesting concepts and rumors out there and some of them actually seem believable.
For example, Patently Apple reported that the Japanese company Sharp will be creating big IGZO displays for the new iPhone device. This company already has a very large partnership deal with Apple and there's no doubt that Sharp has the capacity and technology to handle the workload that the iPhone 6 would bring.
Anyway, as I dig out more I will be sure to let you know :)