Weak hand wavy arguments. We don't know what consciousness is, so we can't conclusively say machines won't attain it. Recently a fish passed the mirror test. Seeking novelty and even comedy could be automatically learned and formulated I believe some day not far away. We can keep trying to move the goal posts but as it gets more and more difficult to make any pragmatic distinction, we'll just have to chalk this one too for machines. Then we can deal with equal rights if we're still in control.