This is not really anything new, people have been loading NIFs in Blender, NIFskope and such for a while now
However, the main problem is that there are many sorts of nifs, and not every nif-editor exports the data correctly for ZT2 to display it. That is why model editing is yes possible, but difficult because the programs that do edit and export NIFs correctly cost money and take a while to learn, and it is still challenging to get edited models in game and working correctly.