Well, The Nikon D7000 and the D300s I believe, both have 39 AF points but of those only 15 are cross type. One of the things I love about the 7D is that all 19 are cross type. I'm ok with the number of AF points on the 7D. I've never found it limiting. However if they do increase the number I would prefer they maintain the density of the 19 and just add a layer around the outside of the diamond if possible. All cross type.+1
Keep the densitiy, maybe add a few points for better spread, and keep it all cross-type.
If you come from a camera with line sensors at the outside (XXXD, 10D-30D, 5D, 5D2), you really appreciate the fact that the 7D's AF points are all cross type. The 7D's AF gives you the freedom to concentrate on composition without having to worry about using an AF point that might potentially not work for your subject.