There's a chance Canon could be replacing the 70-200 f/2.8L IS in 2009. The lens will be 8 years old since it was launched. It will have a new 4-5 stop IS & improved optics across the entire range.
If it is launched in 2009, logic would say it'd be launched with the 1Dx. Same source says Canon will also do away with the non-IS version of the lens once stocks deplete. That could be anywhere between 2009 – 2011.
Personally, I don't think we'll see it in 2009… but stranger things have happened.