That's exactly what they're doing to be fair. They announced like 10 new Marvel series and the same for Star Wars. But that's just two franchises, which is why it's important to implement The Fox stuff. All former, current and upcoming Fox/FX content are now technically "Disney originals". Family Guy, Simpsons, Bob's Burgers, What We Do in the Shadows, American Horror Story, Fargo, Always Sunny etc. are still running which means new content pretty regularly.
If Disney, Amazon, HBO and Netflix are left as the survivors of the streaming war I think it's a good mix of enough competition to avoid a monopoly while not having so many that it's hard to watch the stuff you want to.