Epcot is also interesting because they will also expand from three (Test Track, Soarin', Frozen), to at least 5. What I will say though in your hypothesis is that Ratatouille has the most generous capacity out of the lot (>2K real world). So I don't think long term it will be tiered above the aforementioned. Epcot I could see doing away with tiers, especially if they are able to make Coco or eventually imagination attractive again.
I deleted a sentence about Rat's capacity being high which may disrupt my prediction.