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It would be, but i'm sceptical that they will do it for fear of cannibalising 1 series sales. It is interesting to speculate as to whether the merging of the 1 series lines might be indicative of a wider policy (i.e. merging of 7D and 5D lines)....
Sadly i can't afford it if no matter what they release, so its a bit moot to me.
Count me doubtful as well. Canon's always been pretty big on establishing marketing tiers and protecting its flagship cameras: just look at what happened to the 60D. If they nixed the 7D the xxD line would have to go back to being the flagship APS-C camera.
Also, the situation here isn't exactly the same--people with APS-H cameras still used FF glass for the most part. Merging the two formats didn't render the existing user base's lens lineup obsolete as it would to 7D users if the 5D/7D lines were combined.
IMO the main reason the 1D / 1Ds series as separate entities until now was because they didn't have competition from Nikon. With the D3 Nikon took a lot of the user base with a camera that had FF, great high ISO and high frame rates. The 1DX seems like Canon's effort to take back the market they lost to Nikon.
Though there's really not any point in speculating, but I think it's a safe bet that Canon will continue to protect their 1D sales by placing the 5D3 in a different market segment. Whether this will be down to inferior build and a flip-out screen (a la the 60D), lesser AF, or a high MP but poor iso (a la the D800) option remains to be seen.
Personally, if they re-release the 5dmk2 with more than one damn cross-type AF point and the ability to re-assign the front/rear dial functions I'd probably buy it. Oh hey, front dial is aperture in Av? Well now it's shutter in M. Ha-ha! (seriously, who thought of this). And I can't count the times the camera gave me the nope.jpg AF blink, refusing to even try to focus in EV5-8 situations with the peripheral AF points--only to bang on focus without hesitation once switched back to the center point. Better ISO, a better damped mirror and lower shutter lag would pretty much be gravy.