I was there the week of July 4th, and Disneyland Park was nowhere near as crowded as it was when I was there for Presiden't Day weekend. The longest wait I saw for Indiana Jones and Space Mountain was 45 minutes. President's Day they bothe were at 90 minute wait times throughout the day.
I personally believe that Carsland is simply cannibalizing Disneyland's guests. While it may be true that people are probably going to visit DCA first, I don't think the number of guests flocking to Disneyland later in the day is significantly more than it was in the past. Enough Disneyland guests are leaving when DCA guests are hopping to DL, so it is essentially a wash. For most tourists, Disneyland is a stop on their Southern California trip. And I have a feeling many guests in the past simply didn't view DCA as worth their time. So the guests who would have stayed at Disneyland and not hopped are hopping over to DCA.