You can't say Apple absolutely won't release a new non-retina device, then pretend that they didn't do exactly that with the iPad mini.
But the number of those that will also demand that pixels be a certain size - larger than the current ones - and that the resolution not exceed a certain upper bound is, in my opinion, minuscule. You may disagree, and that is fine. No need to debate the point.
No, I'm not saying people specifically want larger pixels. What a silly notion.
What I'm saying is that, given the design constraints Apple tries to work within, a retina iPhone Plus is going to be exceptionally difficult. It will either have to be some sort of "super retina" that would be very expensive, lead to poor yields, and gain no benefit (beyond retina, smaller pixels become exceedingly useless).
The other choice is to make an entirely new resolution and pixel size. That's possible, and if they have to do it, they just might. But I do believe Apple would rather have larger pixels to keep things simpler for developers in order to make an iPhone Plus now, rather than make nothing, or making an impossibly expensive and poor manufacturing yield rate of a proper retina-but-multiple-of-some-existing-iOS-screen-dimension iPhone Plus.
I am eager for a larger display just like you. You can have all pixels you want on it? Can you accept that Apple will take your number and add a bunch more to it for folks like me (and the masses)? If you don't want to use all the pixels, that's absolutely fine by me. Perhaps apple will provide a facility to run non native res like you can on a Retina Macbook. Then we're all happy.
I do think that that's a potential down the road, but Apple doesn't have the developer support in place to make that feasible today. It would have to be paired with a significant change in iOS support and guidelines. It's possible they could do this in iOS 7, but I think it's the sort of thing Apple would rather hold off on if they can, even if that means releasing a non-retina iPhone Plus. The precedent for this is the iPad mini, which you so readily dismissed above without the slightest justification.
Yes, all things remaining equal, a higher-res iPhone Plus would be better than a sub-retina iPhone Plus. But all things aren't equal, and a non-retina iPhone Plus is better than no iPhone Plus at all!
And to those saying that a larger size at the same resolution is pointless, just look at computer monitors or TVs. People uniformly prefer 50" 1080p screens to 20" 1080p screens, when space and budget allows for it. Even if it was just the exact same resolution of the iPhone 5, only 4.x" instead of 4", there'd still be a significant number of people who would rather have the larger size over the sharper image of the smaller model.
And the nice thing about it is, since Apple will clearly sell both a larger and a smaller one, those that prefer one over the other will be able to buy the one they'd prefer, instead of being stuck with just the only one that's available!
It's a complete win-win. I don't understand where all the complaints are coming from. With an iPhone Plus, you lose nothing, and gain extra choice! What's wrong with that?