I would argue that Tesla became era-defining by the efforts of Musk; and I get the impression that within the USA Tesla is still leading with regard to electric personal transport.
Worldwide is a different matter: other brands have learned lessons, replicated what he did right, improved on what he did wrong — so while he's still defined the beginning of the era of electric cars, he's no longer important to the ongoing success of them.
I would argue that Tesla became era-defining by the efforts of Musk; and I get the impression that within the USA Tesla is still leading with regard to electric personal transport.
Worldwide is a different matter: other brands have learned lessons, replicated what he did right, improved on what he did wrong — so while he's still defined the beginning of the era of electric cars, he's no longer important to the ongoing success of them.