Well there won't be any updates for existing DLCs but i'm sure we will have new "Main" updates in the future.
As for lights, I'm guessing that it's too complicated to implement it in the thememaker toolkit. But this doesn't mean they will not update it one day to have lights. And even if this never happen, I'm sure we will have an "illumination map" options. If not when the thememaker gets out, then later.
For those who are new to 3D, illumination map is very common and is part of the material layers (diffuse map, normal map, reflection map, gloss, etc...).
It allows you to tell which parts of your 3D models as to glow. It does not replace lights because it won't affect the terrain or other items near by, but it will glow in the dark instead of being all black.
So this option, that i think is "easy" to implement in the thememaker, would allow cool stuff like glowing eyes, light sabers, electronic lights, etc... And it would be easier to hide a light in the 3D object and make it feel like it's coming from that object.
Illumination map do exist in this game, a good example is when you turn off a light, it doesn't turn off this map, that is why all the lights are still visible in the dark.
(Sorry for my english [big grin])