I think if they have any sense they'll go with a 19" display that is true industry standard 16:9. It would be about as short as a 15" display but WAY wider (take a regular 14.1 PB/iBk screen, add an inch to the top and 2.5 inches on either side and that's what 19" 16:9 would look like) and the two together would be perfect for Final Cut Pro editing--timelines and and program on the 4:3 display, then composite playback on 16:9 19" screen. If they did this they could keep the price reasonable, as a 19" 16:9 screen would be about 9.5" x 16.5"--not very big, but there is an emerging market for 16:9 monitors that will only increase over time. Heck, it wouldn't be shabby for watching DVDs, either, for us audio production guys...
As far as the 22" goes, a 19" would essentially replace it. People needing HD monitoring would go for the 23" with the higher resolution, and those that don't need HD referencing would invariably opt for a slightly smaller yet spot-on 16:9 monitor instead of the taller 16:10 22" display Apple currently offers. Why band the top and bottom, even just a little? Sell it @ well under $2k and video guys would buy them on the spot.