When they say "It’s not something that Chapek and his team can really fuck up, especially as shareholders and people within the company look to it as a core part of their future," I agree, but I read it differently. In theory, it's not possible to fuck up Disney+: Just take content from the Disney Vault, price it appropriately, and slowly convince families to transition away from their expensive DVD collections to streaming. It's an exploitative and rude business model, but solid and time-tested.
But, that said, the circumstances have shifted following The Mandalorian's success. Now, Disney+ has a new baseline for not failing: It must produce a new Mandaloranian-level hit every season. This suggests that, like Fox's TV programming in the 90s and 2000s, Disney+ will have to invest in many risky experiments in order to continue being worthwhile, even though the bulk of their subscribers only care about the shows currently being milked.