There is always room for improvement but... but... but... but... but... but... it will always be more expensive than a Nikon solution.Really???
Well, the current 200/2 is quite good, not that much room for breathtaking advances & the 800/5.6 is...rather special. Most of the potential target demography would fare better with a 600/4+TC. I.E. likely great products with a nice showroom factor, but not much practical impact.
Can I get a 800mm IS II exceeding $20,000? Can I hear a 200mm IS II exceeding $8,000?
Improvements of up to 25% less weight, Power Focus, IS mode 3, optical improvements, USM upgrade, IS upgrade.
I do expect the upgrades to happen by...
It took Canon 12 years to upgrade their v1 SuperTele IS lenses to v2 SuperTele IS lenses and the 200 & 800 were marketed in 2008.
So the rumors for a 800 and 200 replacement are very much true though a tad premature.