No, we haven't and it's not about that, anyway. I'm talking registration distance here - and its implications on optics. You mentioned the DA 15mm, but that's an f/4 lens - what if you could do an f/2.8 with better corner to corner sharpness instead? Fujifilm has an 18mm f/2 pancake, so it might be possible with a smaller registration distance.
Having an unused space between the lens and the shutter serves no practical purpose. Yes, you can design a camera so it would have a suitable shape; perhaps something resembling a thinner (but still comfortable) K-5, or some retro-styled camera with a deep grip.
You could also have some really compact cameras, with matching pancakes and retractable zooms - in addition to larger offerings. You could alter the design according to the market's response. Unless you'd fall into the "flat, thin" trap, you have more freedom in designing your cameras (as much as I like the K-1, it's a bit too thick for my hands).
If you don't do that, you might as well make a DSLR.
You should know me by now, silly ridiculing tactics ("just so 500 people in the entire world") don't work with me; they only tell me you don't have real arguments
Your proposal would put Ricoh Imaging at an disadvantage, while the argument - using "all the existing small Limited lenses with KAF4" - doesn't stand because those lenses don't
exist.
That it requires a massive investment - true, but this is what it takes to seriously compete on the MILC market. There's no shortcut, no "magical" workaround; if it cannot be done in 2017, simultaneously with the D FA line, it cannot be done (which is actually my point). But on the long term, I'm convinced this is the only reasonable option.
By the way, I'm staying with DSLRs; there, that space is properly useful (and retrofocus wide angle design is necessary, not just a waste).