It could have definitely been worse, with the leak of the fused secrets or a breach to integrity of the microcode (the two things that together constitute the TCB, which put simply is the only piece of the system you assume will never be broken).
All in all, assuming a microcode update can counter the attack as Intel claims, sealing and attestation secrets will be rekeyed via the KDF rooted in the fused keys, so that you can start afresh.
Of course, operationally speaking, that is a total pain but it is frankly remarkable to see this kind of deep recovery strategy finally built into consumer devices (and yes, I know DRM is unfortunately the main driver, but there are still some very legitimate use cases).
>> flush L1d (or prevent things from accessing the same L1d via e.g. core pinning) and you're fine
No, you are not fine. As the paper explains, an adversary (which is by definition more privileged than you are) can operate between the moment you use secrets in L1 and the moment you flush them out. Only the CPU (silicon or microcode) can assist you in the flushing of L1 when you exit enclave mode.