Even with the expansion, it's a terrible timeline.
Iger hasn't expanded adequately, but the bigger issue is allowing EPCOT and DHS to practically go on life support with completely closed or unused areas. DHS essentially wastes the entire backlot area, Streets of America is a joke, LMA needs an update, and Sounds Dangerous/American Idol are unused. EPCOT has unused Wonders of Life, Imagination Pavilion, and several attractions in desperate need of TLC.
Disney should get all 4 parks completely built out with every building utilized. After they are all completely built out, then focus on expanding.
I'd vote to do things concurrently, but I have little confidence in their ability to manage multiple projects simultaneously. They should have done the "upkeep" over the last 10-15 years. Now, we kind of need refurbishment AND expansion.