History has not proven this out.
See: Africa pavilion preview during Epcot opening tv special, heavy promotion of Beastley Kingdomme in TV specials and souvenir videos, the preview and huge model of Western River Expedition, Muppet Studios and Maroon Studios announcements for D-MGM...
The thing is, when those projects were announced, that was in a day and age before social media existed and the internet really took off. With social media and internet, it may be a bit harder to sweep that Avengers under the rug. People may stumble upon concept art upon a Google search, and wonder if that will open with Avengers campus.An if you want a recent example, the Main Street Theater in WDW. Announced right at D23 and swept under the rug not too long afterwards.
Gotta' be unfortunately blunt here, if it's not under construction...it could very well be put under the rug since Disney is no stranger to going gunshy in times like this.
As for the Main Street theater, I don’t think nearly as many people would care about a theater as much as an E-ticket Ride.