I guess Canon is struggling with Nikon's offer and its price point.
With the 5D3 Canon managed to give event photographers the best low-light shooting instrument on the market, as it is supposed to be coupled with 70-200 L f/2.8 IS USM and the new (a coincidence?) 24-70 L f/2.8. Rumours about new L-grade 50mm and/or 85mm would complete the line-up, so I find them quite likely to be true.
On the other hand, to anyone who is not a pro event photographer, I would suggest to buy D800 and a couple of third-party primes over the 5D3. More MP, more DR, more color depth... less money. Much less.
So what about new FF cameras? Canon is forced to produce a high MP camera to compete (if for nothing else, at least just for the sake of its reputation) with Nikon, but in which price segment will it be? 5D3 is already considerably more expensive than D800, where would you place a higher-end camera? They cannot compete if there is a 1000€ gap in price. Note how Nikon's D3200 forced Canon to rush the release of a 650D, which honestly no one was craving for. Most people still have been buying the 550D over the 600D. A new high-MP FF body should lye in the same price league as D800, and in my opinion Canon at the moment is simply not capable to do so.
Same problem you would have with a entry level FF body. Nowadays you can buy a 5D2 body for about 1700€, but the AF alone keeps me (and many others, I guess) from buying it. The 5D2 looked already "old" in 2009 when the 7D came out with its significant better specs, if Nikon manages to produce a good modern FF camera (24-26 MP, good AF, DR, etc..) and to put it in that price league, again, there will be no competition.