See the answer to the parking issue isn't to keep Toy Story. Toy Story is actually considerably larger then the Mickey and Friends Parking Structure. Yet it holds a fraction of the spots. If Disney wants to solve the issue, they need to build a new parking structure.
You're right that those issues need to be addressed before or while Disney is building the 3rd gate.
I think they can fit the park in. It'll feel different then the more sprawling parks they've been building recently. Very dense. It can be done though.
You're right about that actually rteetz. There's a small parking lot just between Carsland and TOT that seems perfect.
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There are even two guest paths that just lead to nowhere (yet). Strange choice on the designers part if you ask me. It'll actually be a lot like DHS with TOT and RNR (Marvel) drawing people down through the land. They'll also be access to Bugs Life and Carslands.
Here's one more picture to help you visualize the sight line:
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Access does seem limited which could kill it being here. It does seem to be begging for something.