So roughly around this time last year, Darc successfully converted me to an Apple consumer.
I have had my hands on all of them and aside from Apple dropping support for 3GS and 4 all phones are functionally identical. Atleast the functions that I would use on a daily basis.
I think you say that now but if you had to go back and use a 3GS, you would notice a massive difference, with the non-retina screen especially.
One thing that I am expecting though is that the same size and shape is retained, the biggest reason why I bought the iPhone was that it is still the size of a phone and not a notebook or a tablet. I don't like S3's or Note 3's as they are large. I like my small iPhone screen. I don't want iPhone 6 to be XL.
Honestly, I would be surprised if Apple didn't
release an iPhone with a larger screen. Like you said, their phones lately have
been fairly identical, but I would simply call it evolutionary (big speed upgrades but minor new features) instead of revolutionary (lots of new features that shake up how we think about or use our mobile phones). The retina screen was the last big revolutionary feature, and since then, there hasn't been much (iPhone 4S had Siri, which has become the "voice" of the iPhone when it comes to marketing purposes, but I don't think many people actually honestly use it as a feature or care about it, so that was a flop; iPhone 5 had LTE, but that was late and Apple was playing catch-up).
Right now, I would say the iPhone 5S is pretty much identical to the iPhone 5. In fact, I bought an iPhone 5S and returned it because I could hardly tell the difference, and I'm not a hardcore phone user. Sure, it was faster, but not in a way that's really all that noticeable to the average user, and it does have the fingerprint sensor, which is cool, but I didn't see it as worth upgrading over, so I returned it.
So that goes the same for the 5c too. To most people, the only difference is that the 5S has a fingerprint sensor, and its colors are more 'mature'/'deluxe' looking. That's really the only big differences... is that worth $100? probably not, to most people.
A larger screen is one of the few things left that many people have been asking for that Android has and Apple doesn't. I can easily see Apple creating an iPhone with a larger screen and placing that at the top as their high-end iPhone offering. They would likely then still sell iPhones with the current screen size in an assortment of colors, maybe now with the fingerprint sensor (or maybe not? maybe they'll keep that as a feature of the high-end model only). Anyway, Apple needs a big and obvious differentiating feature between their high- and low-end models, and a larger screen could easily fit that role.
That's just my opinion, though, I'm not basing that off of any solid or concrete research.
I do hope the phone comes out in June and not later cause Lumia is driving us crazy.
I doubt that is going to happen. A new iPhone comes out every 13-14 months, and I cannot see them releasing a new one just 9-10 months after their last iteration. It will likely be in October.