I think on the one hand it will be worse but I don't think it will be much worse. We already know that half of the seals are already gone. It's possible that the DO influence will double but it may actually diminish some. Think of water coming out of a blocked hose. There's a point where it's seeping through, a point when it's shooting out from being forced through a small opening and a point where it's running strongly but not as far. The bubbles of evil whetehr they represent seeping or shooting they should stop as soon as the seals are removed. The blight might extend further but I think the DO might have more trouble making his power spread as far as he can in the "shooting" stage. Remember the WOP took place for hundreds of years, the world can survive the current size of the bore at least to a degree.