I would argue that 4.7 is more of a "normal" screen size than 4 is. Not saying that they shouldn't have options and I'm certainly not opposed to a new 4 inch phone, but I think realistically the 4.7 would be the normal in most peoples eyes today and the 5.5 and 4 the out of the norm options for people with preferences in either direction. Heck, I don't actually even know anyone with a 6 or 6S but I know plenty with the plus versions. So I think the "normalcy" skews towards bigger. I know there are people who prefer the smaller phones and I get it, but I think people need to accept the fact that what was "normal" 4 years ago isn't the same now. With that being said I do think they should have options for everyone. My hope for the future of the 4 inch model is they keep it on par with the other sizes. I really think keeping them all the same (as close as possible feature wise) and just giving people the choice of screen size without compromise is the best route. If apple could reduce bezel sizes I would take an even larger screen honestly. My 6 Plus is big, but I've never had a problem with pocketability or usability. I don't really know what to compare them to but I would assume my hands are average. Now I'm at a point where I can't really even imagine going back to a small screen.
There is nothing normal by attaching a brick to your face (5" plus phones) while you talking