2mm on the wide end is quite a bit, especially for wide-angle junkies. That is not to mention anything of the jawdroppingly good optics on Nikon's 14-24. I agree, however, that an overlap doesn't make a lot of business sense, especially since the 16-35 is already f/2.8. For that reason, I think that if Canon does release a 14-24 (and I hope they do!), it will probably replace the 16-35 rather than becoming a third wide-angle zoom in the lineup. If it does happen, I'm sure the loss of the extra range would be bemoaned by some, but at the price it would need to be there shouldn't as much concern about complementing it with a normal zoom of some type. The switch to a bulbous front element could be troublesome, but then again it's not like the already-excellent 16-35 II would be going anywhere.
As for actual rumors, I've heard nothing of the sort.