Some things to consider. The competition isn't from Nikon alone. Sony is introducing an under $2K FF DSLR, so it would make sense for Canon to answer that in order to avoid losing market share.
Canon doesn't "answer" to camera models released by competitors. It just doesn't work that way. They give part of their product philosophy in the Canon Camera Museum website where they detail the development of the T-90, and in one interview an executive talked about their five-year planning method and model structure pyramid concept.
Each manufacturer has a unique view of its market and a unique product philosophy. In a rare case, the product philosophy might even be embodied in a single individual. One such case was Olympus' magnificent OM-1, which was the brainchild of designer Mr Maitani--so much a product of his personal philosophy that "OM" stood for "Olympus-Maitani"--not a common celebration of the individual in Japan.
Canon's view of its market is not the same as Nikon's view, nor is Canon's product philosophy the same as Nikon's. Nikon, for instance, has always been the ultimate PJ camera since their rangefinder days, and their higher-end models will always show a distinct design slant toward PJ-oriented features.
Since the 60s, Canon has always leveraged its electronic prowess, and that's what you will see in their products.
Between their long planning cycles (five years is equal to "after I'm dead" to the Western business mind) and their different worldviews, neither company sees any particular model of a competitor as "something we must answer." They don't intend to have a direct model-for-model competition, rather they have a competition of entire product lines based on which company has the more accurate view of the market and how the market can be subsetted.
This does not totally insulate them from true technology disruptions. When Minolta released its Maxuum 7000--the first commercially viable autofocus SLR--it caught Canon only a few months away from releasing their T-90 (probably the most awesome manual 35mm SLR ever made).
The Maxuum was a true disruptive technology that instantly obsoleted everything else in the industry. Canon had no choice but to release the obsolete-at-birth T90 and a few more manual cameras that were also too far along in production to halt. It took them three years (probably very long years in their R&D department--there may have been a few designers who committed hari kari over the decision to dump the FD mount) to field their own autofocus camera.
In those three years, it was obvious that Canon could not simply "answer" the Minolta Maxuum 7000. That would put them three years behind the power curve. They had to develop a system that, when fielded, would be more advanced than any competitor could be in three years...and the EF mount did just that.
I believe we saw Nikon at the end of their previous planning cycle during the two-years or so of lackluster releases from them (while their marketing division was still saying "We don' need no steenkeen full frame" to sell the cameras of their previous cycle, they were in a cycle of calmly planning exactly the opposite), and then we have seen the results of their latest planning cycle in the flurry of releases over these past few months.
Today, Canon won't "answer" the Nikon D700. We don't know where they are in their current 5-year planning cycle. They could be near the end, and we may in the next year or two see the results of a new planning cycle, which will be intended to place Canon ahead of what Nikon or Sony can do over the course of their current planning cycle.