Nothing (except lawyers fees).
It was Eberhard who sued Musk trying to get the courts to declare that only he and Tarpenning can be called co-founders of Tesla.
And that backfired because the judge declared that, actually, Musk and JB. Straubel are also co-founders of Tesla.
https://www.tesla.com/blog/judge-strikes-claim-who-can-be-de...