Big screens are a matter of preference, but Apple isn't particularly inclined to catering for everyone's preferences.
The 3.5" screen is really a matter of principle to them - it's the size they've decided a smartphone should be, and the size they've designed their UI to fit into (just like the iPad being the size they've decided a tablet should be) and we'll probably never see a device they put out that changes that anytime soon without a really good reason.
Well, a good reason might be that LTE is power hungry so thus it requires a larger battery if you expect to maintain performance with the current iPhone. So, it's possible that a larger screen would be, rather then the goal, merely a byproduct of the battery need. Almost hiding it in a way.
That being said, I think a 4.6" claim is off the mark. But I could see a 4" one easily being released.
Wirelessly posted
Good for 'old people'? I'm 62 and I will speak for myself. The currant screen size is fine, no reason to change it.
Well it's nice to assume because it works for you that it works for everyone. I know for a lot of you, the screen size is fine as it is. But there are plenty of people out there, such as myself, that find the current iPhone screen just too small. I have some vision problems, so it's a major deal-breaking issue for me. Seems like some other people have some vision issues too...cause the view that "it's fine for me so must be for everyone else too" seems pretty myopic.