Apple has certainly survived with highly effective management. But they have not created a single all-new/revolutionary product since Steve died. One could give them half a point for the Apple Watch but it's pretty obvious (tiny iPhone on your wrist) and the project was likely started by Jobs before he died.
I think Tesla will follow the same path if/when Musk leaves. They will be a company that provides good products for their customers and good value for shareholders. As
@whatstevedid says, many things will likely improve w/o Musk. Bringing in a management team with actual manufacturing experience will improve things like communication, parts availability, logistics, etc.
But the outside the box innovation will end, as it has at Apple.