Could this be a lens that goes head to head with the Nikon 200-400F4???
It could, but then the rumor would be completely wrong. A lens with half the zoom range, larger aperture, much higher weight and 2-3 times the price would hardly be a 100-400 replacement.
The current EF 100-400/4.5-5.6 cost $1,500. A 30% raise is reasonable. A 60% is borderline. Anything more and I go for the Sigma, which is $500 cheaper than the current model to begin with.