I think this is entirely a fan-made theory. They look to merchandise sales and future plans with the IP when determining their drive to include a property in the parks.
There is a massive laundry list of other animated films that would take precedence over IceAge.
The only reason Pandora is a maybe is that it already has a fleshed out plan (likely would just be Flight of Passage at WDSP) and there are internal hopes for the franchise with a 4 movie run this decade. There are major cost savings to be gained by cloning a film-based attraction.
Look how long it took them globally to get Marvel into their parks and that was an active, high merch producing IP. Besides the fact that it isn't a very good film franchise. Can you even find a character in their parks yet, or merch, or even merch at your Mall Disney Store?
IceAge is DOA.