Haven't read through all the comments carefully but has anyone thought that maybe this is in fact a 1D5 and the specs are bang on except for one... it will still be APS-H. A replacement for the 1Ds3 could follow, be announced simultaneously, or perhaps a new line to replace the flagship studio camera.
In fact, just prior to reading this post, that's what I suggested in the thread on irony.
I haven't been keeping up with reading the posts for a couple of days and as I scanned through all the posts speculating as to why these specs don't make sense it occurred to me that there were a couple of themes... a) resolution is a step back from 1Ds and b) spatial resolution is a step back from 1D4 both of which ring true. On the assumption the rumour and spec list is not a complete fabrication what 1 change (Occam's Razor) would resolve both issues. APS-H would do the trick... if so, this spec list fits nicely for a 1D5.
Now that I think about more... a lot of the recent talk on the forum has been that APS-H would be discontinued to the point it may have become assumed to be true so the rumour source and all the comments just assumed it must be FF.
Let's say a new APS-H sensor, even at 18MP, has even better DR, lower noise, and better low-light performance that the 1D4 or 5D2... would it be the perfect sports, wildlife, AND wedding photographer's camera? 16MP maybe wasn't enough for wedding photos but 18MP is closer to the 21MP of the 5D2.
If anything I'm speculating makes sense, this spec list now appeals to a wider market so if Canon could sell it for say $4200 (instead of $5k for the 1D4) would it become the easy choice for working pros over a 5D3... that way Canon can increase the resolution to 30+ MP but keep the AF performance, etc. of 5D3 down to differentiate it and keep it positioned as a landscape, portrait, entry level studio.
Now big question, would they then venture into MF to replace the 1Ds3 as the flagship???