The big selling-point of Lightroom for me is that is minimize the tedious, monotone actions needed by me to develop large series of raw files into good-looking, well-organized digital libraries. My suggestions are primarily in order to improve on this main benefit.
/* consumer-style features */
+ Facial/Motif recognition would be great. I'll happily tag my first 100 pictures, but if those faces are recognized in other pictures, why not suggest the same tag?
+ Instead of presenting an import as a chronological list of 100s of images, I'd like some smartness in presenting the "likely" good shots first. Focus/camera-shake, over/under-exposure, open/closed eyes etc.
+ Some modules seem overly constrained. Why do I resort to MS Paint occasionally for simple things like putting two images side-by-side in an image, instead of wading through endless options in the LR book module with seemingly pointless e.g. margins enforced upon me?
+ an iOS/Android lightroom-"light" app. Should give access to catalogs shared on a NAS, the ability to search and view images in a UI familiar to LR users. Additional points for being able to rate and tag images on the device, but no need for the full develop module, and images could be pre-rendered by the PC/Mac to jpegs if necessary.
+ Ability to keep source folder (sub) structure when exporting.
/* enthusiast features */
+ 2nd monitor should zoom in on an area defined by the active AF points. I see myself manually doing this all of the time to check focus of e.g. eyes in portraits
+ The ability to combine images into one edited logical image (HDR, side-by-side, layers, etc)
+ add "skin tone" to the wb picker
+ The possibility for true raw histogram and exposure correction (switch early stages of processing pipeline to camera native "colorspace"?)
More snappiness, exploit GPUs if that makes sense. Enthusiasts may have 8+ cores, 256-bit SIMD, large and fast flash drives. How well does LR exploit this? How well will it in the future?