Zen is a success. But Zen is hardware, and AMD is (historically) a hardware company. Delivering software is hard, even if you're a software company. I wouldn't take it as given that a good (hardware) CEO, vision, and board support are sufficient to build the required software organisation, especially given their track record on this front to date. It is more likely that Modular is AMD's software savior. I won't speculate on how probable that is.