Instead of remodling the world which I think would probably not be a good idea for the reasons stated above what about simply burning the place out. A wall of fire as far as the eye can see several miles into the blight.

I would guess that one would have to do several runs as you can only channell as far as the eye can see but if Rand were to gate into the top of a mountain in the blight he could see for a good distance. It would kill a lot of shadowspawn, both trollocks and the sort that grow like the deadly insects and trees. Not only do you damage the forces of the Dark One but if the armies of hte light do have to fight in the blight, the place will not be quite as dangerous with trees etc ready to kill you.