Haha thanks.
This does seem like the only way to properly increase capacity - you can't really run two-car trains on Crush, and you can't only double-up the coaster section because the vehicles would still have to get through the same outside drop and dark ride.
There are probably thousands of reasons why it couldn't happen and even more why it wouldn't, starting with the fact that Crush #1 would have to close down for quite a while whilst the new queue was joined on and the loading dock switched around.
It'd also be quite overbearing to have an attraction that big so close to the main path, it'd cover a
huge area. Though two soundstages side-by-side like that would certainly look more studio-like...
Objets d'Art just kinda means "little things of value", so it'd be a general Pixar/mostly Nemo shop and a good way to get that sorely missed character in there. The pre-show projection scenes would also allow a lot more of the characters to be seen. One of the negatives of the ride is that it's not actually very "Finding Nemo-y".
The new entrance could be like you're walking into a sea cave with the tide out:

And through what look like aquarium-style windows you'd see the characters swimming around in the supposedly water-filled Studios 4 and 5. (That's kinda how the original concepts made it look, before they changed the whole pre-show to dry land/harbour.) You'd then climb the stairs up onto the harbour.
Oh, and with 2 coasters you could offer Fastpass easily.
I wonder how much this would actually cost? Even if Ratatouille and more are built, Crush is still going to be right there, the first thing you see in Toon Studio. The queue hasn't gone anywhere in two years. I normally stick up for Flying Carpets, but heck - dump it and invest in a plussed Crush, pleeease!
Edit: And of course, Dory's Objets d'Art would also mean ON-RIDE PHOTOS could be sold. Seriously, they'd pay for the 2nd coaster with those alone within 5 years.