I think this is exactly right. There is some fudging with the cost (this seems to be a common theme with Elon) by pre-including savings and rebates Etc, but the fact is this makes a solar roof something different than a set of panels across an existing roof. The durability question, and the weight per sq foot will be interesting.

That said, the combination of the PowerWall and the roof might actually make it more amenable for power companies since you could grid tie "for emergencies" but lower your total overall power budget and help avoid the evening surge (max grid usage in the Bay Area is about 5:30PM, solar is off-line and people are coming home from work, firing up appliances (like cooking dinner, getting a beer from the fridge which turns on the converter) environment systems (heating/cooling) are activating to bring the house to the 'occupied' temperature, Etc.

If your house uses its PowerWall for all that energy you'll appear as a much smoother non-load on the grid.