Yes, I actually wrote about this already in my own thread Thoughts about wc3 changes. I too would very much like to see this, there are however some issues with adding the bloodelf as some of their units already exist in the human faction. The naga however should be easy to add in without having to piss of any conservative fans for changing the human faction.
It is very possible that the changes applied to the world editor will finally allow the modding community to add them as a playable faction without having to mod the whole game. However I would prefer if blizzard did this instead.