That article has such a weird title like it's some risky bet. Disney's "Media Networks" ie TV revenue is 44% of its operating income, it's Parks and Resorts is 34% of the companies revenue. "Studio Entertainment" ie films is only 15%. Of course, Iger is putting a lot into streaming, that's where the company's money is, not the film business.
This is also why people should not be thinking Disney shows are going to be some low-budget, hallway fight shows. Disney+ is going to be the flagship earner for the company right alongside their normal cable services, they are going to be sure to invest a lot in it to attract and maintain viewers.
Except that the what Disney+ is looking to replace/usurp is the TV revenue. Everyone knows cable is falling, and all of these content creators are hoping they can build up their platforms faster than the demise of cable, which is in no way, shape or form a guarantee.