In theory X.509 could be about side topics such as CSR or CRL, but certificates would be appropriate for that anyway. In theory certificates could be encoded differently, but who does that?
NO! x.509 != certificates.
Closely related, for sure, but:
My personal preference is no.
My startup will soon be releasing a kind of certificate that isn't based on the x509 standard.
The whole crypto currency phenomenon has made many smart people examine and innovate on public/private key scenarios... so that might cause a new version to become popularized