From history, I think announced prices are not far from reality when introduced in the market. Also, don't hold your breath: prices for new lenses are ALWAYS higher than previous generation due to enhancements and new material used.
Just take these examples: 14 f/2.8L II, 24 f/1.4L II, 85 f/1.2L II, 70-200 f/2.8L II 24 TS-E II were all around 30% higher in price than predessors.
So if your are looking to buy a long lens, well hurry to buy the actual versions...they are all very performant and the price are still decent...
JD