Micro Four Thirds will be (too) BIG

... And I don't mean "successful", though it probably will be that too.

In recent times I've talked a little bit about how it's a shame and a bit stupid that the bigger companies who are finally doing mirror-less cameras tend to go for the APS-C format (same as for DSLR cameras), rather than smaller ones like my current favorite, the Micro Four Thirds format (which is one-fourth of the old 35mm film frame, now called "Full Frame".)

It's simply that:
1) with any format, there is a certain minimum to how compact you can make the lenses. Full frame lenses, especially high-quality ones, are really durn big. M4/3 lenses are much smaller, but still not exactly pocket gear.

I feel that right now, and for the next few years, the M4/3 format is about the ideal compromise between quality and size.
BUT: sensor technology continues to improve. And it suddenly struck me that around 2020, Micro Four Thirds may be seen as an unnecessarily LARGE format! Because if things keep progressing like they have, by then you can get all the quality you need, even for most professional purposes, in smaller sizes.

I think only three things will break or stop that slide:

1. Habitual thinking, especially from Professionals. They want it big. So a number of big cameras will always be around. 
2. How small gear can get and still be very usable. Admittedly M4/3 is pushing this limit already. I'll say the size of the new Panasonic GX7 is hovering around the sweet spot for serious cameras. (The Fuji X10/X20 also feels great in the hand.)
3. When you want shallow depth-of-field, it's easier to get it with a larger sensor. But two things are helping this: higher resolution makes DoF seem shallower, as we can see now with cameras like Nikon D800 (36MP). Also, I think advances in computing can make the camera simulate shallow depth of field, at some point probably better and much more flexibly than big sensors and fast lenses. 

So I think that in the twenties, Micro Four Thirds will have taken over a big part of the pro/enthusiast market, and amateur cameras will be based on smaller sensors. 

Full Frame will still be around for specialized use. I doubt there is much use for the reduced-frame DSLRs (APS-C) though, apart from sheer enertia. 

I don't see why anybody, at that point, will want anything bigger than full frame, so I wouldn't invest in Hasselblad or Phase One. 

An Olympus M4/3 camera with the high-end 75mm 1.8 lens. This one produces all the quality and optionally all the narrow depth of field any normal mortals would dream about. (It seems big, but a similar lens for full frame is twice the size/weight.)

Commercial for the new Panasonic GX7: