I've been thinking for a while that I need to simplify my (terrestrial) equipment - astrophotography is something else altogether! Assume that budget isn't a big issue and if you are short of time you won't miss much by going straight to the penultimate paragraph!
I currently have a Canon EOS 5D Mark II, lenses taking me from 16mm through to 200mm (you can see the full list in my Signature below), a few ancillary bits and bobs as well as a Canon G10 to slip in a pocket when, as is usually the case, the 5D2 is more than I want to lug around. I hardly ever bother with video and my stills photography is largely landscapes and/or dogs, though I have been known to get my kit out at the odd wedding!
My landscapes demand a high resolution sensor and pin sharp optics and, if I must, I'm happy enough using a tripod rather than cranking up the ISO. Dogs, on the other hand, would indicate a camera in the "sports" category as focus can change rapidly, motion blur is always a danger and quite often I find myself out with them early or late in the day when the light is not at its best.
If it were just the requirements of the previous paragraph then the solution would be easy and I'd upgrade to an EOS 1D X or go over to the dark side and consider a D4. The problem is that, except for special occasions, I find myself less and less willing to lug a DSLR around. If I'm going to be tempted to spend more money on cameras I need a pocket-able solution or maybe something that can live in an old school leather case that I can hang around my neck and that can swing around under an arm. I really hate camera straps that have the camera hanging on one's chest - the camera looks like metallic/plastic dribble in that position so far as I'm concerned. But if the camera is living in a case which is swinging about under an arm then it can't be too big or front heavy. As an aside, when I'm out with the 5D2 it usually lives in a belt mounted holster which works well enough but the whole package is still large and heavy enough to be a nuisance in a number of situations.
OK, that's enough about what I don't want. I do want a camera with around 18 million plus (give or take) high dynamic range pixels with a lens system that will cover the (full frame equivalent) field of view of 16 to 100mm (give or take at the long end) with at most two compact lenses (or even one lens!). AF performance and overall responsiveness must be in the dedicated sports shooter category and it should be capable of delivering really clean images at an ISO of at least 800 and preferably 1600. And it must be compact enough that the camera doesn't end up in the metallic/plastic dribble position (see the previous paragraph if you skipped it).
The Sony NEX-7 might be a contender but lacks a native wide angle option. The Olympus E-M5 has more lens options but the pixel count is at the low end and some of those pixels would be wasted as I rarely crop to 4:3. That is also an issue for the Panasonic micro four-thirds offerings. And until the reviews come in there's also a big question mark about the AF tracking performance of both the NEX-7 and the E-M5 in my mind. Maybe my ideal one (small) size fits all camera doesn't exist yet (Canon, are you reading this!) and, being the proud owner of a 5D2 and some great glass, I know I'll get little sympathy. It's just that I get a feeling that nothing about my wish list is impossible: by way of example just cherry pick the best bits from the Nikon 1, Sony NEX and micro four-thirds offerings. It just hasn't got integrated in a single camera yet. Or has it and I've overlooked it?