Consider it? Of course they have - and they've already implemented it. The 1-series bodies can take up to 7 AE-bracketed images, and have been able to do so since the Mk II versions of the 1D and 1Ds (which were available in 2004, a year before CS2 introduced the Merge to HDR function!).


It's also worth noting that although all other non-1-series Canon dSLR bodies can only bracket three frames, on the 7D you can bracket 3 EV steps, just like the 1-series (the others are limited to 2 EV steps). So, with the 7D you can cover a 6 EV range in three frames at 8 fps (i.e. handheld HDR).