Based on the current price (near-2012 retail price) of the 5d3, and without many rebates that I've seen (Nikon D800 user here that continues to see Grey market, refurbed, and lower prices), apparently the 5d3 is here to stay for several more years at the least. And apparently selling QUITE WELL!
My first FF DSLR was actually a 5d2 -- bought in late 2010 -- and served me well. The 5d3 is a huge improvement, I hear, in handling noise, of course AF blows the old 5d2 system away, and general ergonomics. I've held one and like it.....but I switched entirely to Nikon not because of 36MP. My decision was based on its superior UWA lens selections and ability to "push" image in post without all of the banding issues.
The sharpness and resolution of 22/23/24 MP is plenty. Trust me. I've never looked at an image and thought "this is just not very detailed". My best work is from my 5d2 (I did shoot a lot more when I had it). My point: I was a LATE adaptor that was reading (in late 2010) how a new model was "right around the corner". Well, yes, 1.5 years later that was the case. BTW, I paid $2,600 for my now-outdated 5d2 less than 4 yrs ago. I think I sold it for around $1,600-1,700 when the 5d3 was just announced. So I got plenty of enjoyment out of it for roughly $50 in deflation each month. Pull the trigger and get the excellent 5d3. Newer and better will always be the paradox of electronic purchasing. Lenses are the only purchase that truly hold their value in the realm of photog