Originally posted by alpheios I actually thought about that for quite a while and was literally about to buy one but then the 70-200 F4 was announced and I decided to wait for that because I expect it to have better focusing motor, better coating and internal zoom and focus meaning fixed lens dimensions which I prefer.
Those are valid arguments. The AF speed is likely to be improved vs the 60-250 if the 70-200 F2.8 is any indication. Internal zooming is also probable, again based on the other design. Regarding coatings, I doubt there will be a visible difference, the 60-250 is already among the best there is.
The current lens also has the advantage of a longer reach. Ad being available now
In fact, considering that the AF system of the 60-250 COULD be upgraded, the internal zooming is probably the only reason to design a 70-200 F4 instead of using the current design.