Thanks for posting the proposed plan, Steve. Having read it through...whew...I think the maximum of 300 people seems reasonable. There would still need to be a ranger posted at the bottom of the cable to ensure only hikers with that day's permit ascends the cables.
Personally, I'm in favor of removing the cables, allowing only technical means for ascending that part of the dome. There might still be people trying to go up, but they won't get far without climbing gear. I wonder what cable-free routes would look like in that area - perhaps slick rock?