Eug: I agree with you. I adjusted to my Galaxy Nexus when I had it for almost a year. But really it was a joy moving back to the 5 then 5S when it got released. The size of the phone is just about perfect for me. I could go 4.3", I've been saying that is ideal for a while, but I also really like the 4" size. Maybe keep the same physical phone size with the bezels slightly reduced?
As for what Apple will do I think a 5.5" device will likely be next year if they go that large. Apple likes to efficiently ramp up production and I don't think they can hit the numbers they want right now. May also be some other under the hood things they are trying to do as well.
The 4.7" size seems prime for what they can/will do. The Moto X is a very good sized phone with regards to physical size, feel and weight. They can target something similar or maybe a tad larger with some bezel. They will sell like crazy. The only thing I hope is that they don't make it their premium spec phone and the 4" becomes the cheaper option. If they keep the same internals spec wise, processor, memory etc...obviously battery will be different and likely screen res (same ppi maybe).
All rumors at the moment. Time will tell.