I was playing with my DSi the other day and I really like the form factor. It's simple, minimalistic, and the matte finish is a much better choice than the glossy outer shell of the DS Lite. There's really no way to make the DSi any more compact than it already is. Besides potentially cutting some depth (the space above the top screen and below the bottoms screen), the 3DS is pretty compact. I'm not sure a Lite version is even necessary. If anything, I think a revision similar to the backlit GBA is more likely where it looks the same aesthetically but some of the insides have been changed for the better. Obviously, with time, the chipset can be made smaller and more energy efficient and with that extra space a larger battery could even be put in, further improving battery life.
Additionally (and less likely), Nintendo could skip the Lite stage and go right for a DSi-esque revision with bumped up specs. In my little dream world, I would hope for larger higher-res screens with the extra RAM and processing power used to take advantage of said screens instead of just larger screens at the same resolution like DSi and DSi XL. I'm not suggesting 3DSi (for lack of a better name) specific titles. Rather, games could run a 3DSi-mode for sharper visuals. Better screens would also call for better camera and a larger form factor would allow for a much large battery. This could also bridge a graphics disparity between 3DS and NGP. Wishful thinking, but it's fun to think about. I would totally buy this version, no question.