One reader brought up a point I'd been meaning to make for awhile but haven't gotten around to: life cycle speed.
Consider the following progression: Olympus E-P1, E-P2, E-P3, EM-5. Technically, the EM-5 isn't the fourth in a string of high-end Pens, but practically it still represents the fourth generation of high-end m4/3 for Olympus, all in a span of less than three years.
Or maybe this: Panasonic GF1, GF2, GF3, GX1, GF5. Here, the line bifurcated, but we're still five models in, and still less than three years from the first.
One reason why the m4/3 twins are iterating so fast is that they're scrambling to establish and retain foothold, which they've done well so far. Canon isn't even in the market yet and Olympus and Panasonic are already generating very mature product that will be difficult to dislodge. Nikon is still on their initial product launch, one that needs a lot of small things addressed. Sony started a bit later, and is an iteration behind (e.g. NEX 3, NEX 3C, NEX F3 about to be launched).
From the user viewpoint, there are both pluses and minuses to this mad scramble. The plus is that an EM-5 is definitely far better than the E-P1 was, and a GX1 is a very nice upward move from the GF1 while the GF5 has pushed far from the GF2. Iteration has definitely helped refine these cameras. Unfortunately, the downside is that both Panasonic and Olympus have completely devalued the previous generations of cameras. With Cameta selling a new E-PL1 kit for US$199 this week, how much is your used E-PL1 worth?
Cameras aren't investments, so we can't expect them to hold their value. But we're in a situation at the moment where some of these older cameras have almost no value. They're as valuable as consumer film SLR bodies ;~). The danger here is that we're getting mighty close to the notion of "disposable."
No doubt the camera makers would love to get you into their mirrorless system and get you updating your body every year or two. That's an expensive proposition, though. Had you bought all the Olympus E-PL models, for example, you would have paid US$700 or so in early 2010, another US$700 or so in early 2011, and yet another US$700 later that year. Even had you skipped generations, you'd have paid US$1400+ for bodies that are worth about US$500 today (but you'd have two kit lenses to show for it ;~).
Which brings me to another point: the camera companies that are iterating quickly aren't selling body-only packages at all or are prioritizing the body-only packages last in their inventory pipelines. They're taking advantage of their loyal users, who are still eager to upgrade to get better focus performance, more pixels, better low light performance, or better features. Consumers have long memories, like elephants. Fortunately for the offending camera makers, pretty much all of them are doing the same thing, so right now that consumer has no way of punishing that bit of extra sales greed. The Burger King "have it your way" approach hasn't really been tried by any camera maker yet, but I'll bet it would be rewarded by the consumers. Quick, how many "kit" lenses do you own (or have given away or sold for a few bucks)? Are you tired of that yet?
I mentioned a reader email up front, and I haven't actually addressed the question that came up in it: do I think Fujifilm will iterate the X-Pro1 quickly? My answer: no. There's no evidence that Fujifilm has ever seen urgency of iteration in their high-end models, nor do I think they have the resources deployed to do so.
To some degree, the higher the price and specification, the slower the iteration you can expect. That's certainly true of DSLRs (for example: Nikon pro DSLRs have major iterations on four year boundaries, minor on two, while Nikon low-end consumer DSLRs have relatively major iterations on one year boundaries, or at most, 18 months).
So it's fairly easy to say we'll see a GF7 before we'll see an EM-6, or maybe a J3 before an X-Pro2.