One of the central arguments of the 4/3rds mount was that digital camera sensors were destined to stay small, thus, a new mount for these smaller sensors, with a smaller lens throat and registration distance so that the lenses could be smaller and lighter, only covering that 4/3rds mount size.
Of course, Olympus kinda screwed it up by making the throat (meaning the diameter of the lens mount) the same size as the OM mount, which kinda makes it hard to make an inherently smaller camera. And then Canon realized that if they were able to make a even vaguely reasonable full-frame camera, they'd rake it in, which paid off big.
Now, Olympus has always marched to the beat of a different drummer. They made the PEN half-frame system... which I might add was designed for an image size of 18mm x 24mm and is actually a bigger format than the 17.3mm x 13mm sensor of the 4/3rds system and the Olympus OM system, which raised the bar about how small, light, and quiet a 35mm SLR could be.
Olympus has made, for the 4/3rds system, two markedly different compact body styles... the E-4xx series, which tries to be the smallest and lightest normal-looking SLR, and the E-3xx series, which features porro mirrors like the PEN series had.
Panasonic and Leica released a version of the E-3xx series, called either the Panasonic DMC-L1 or the Leica Digilux 3, that was styled like an old Leica rangefinder.
However, the only Leica (or 4/3rds, for that matter) lenses released were huge SLR-ish lenses, nothing like the tiny lenses available for the M8. Which means that you have an sleek and tiny feeling body with lenses that were not correspondingly dramatically tiny.
Meanwhile, Pentax made a series of impressive pancake lenses for their system.
Well, now Olympus has finally caught up and released the smallest and lightest SLR + lens combo on the market. The Olympus pancake lens is cheaper than the Pentax equivalent, adding $200 when purchased as a kit. I looked at the numbers and it's about 20mm wider, 20mm taller, and maybe 20mm thicker than my G7, from what it looks like.
So, in my mind, the new setup suggests that the end of the road could feature a truly pocketable SLR like the Pen F used to be long ago, so that you could stick it in a reasonable sized pocket so as to not draw much attention.