RSA is still here
The last few paragraphs of this article are confused and confusing, and really should be rewritten. RSA is in ubiquitous use today by both TLS 1.2 and TLS 1.3 for server authentication, what with almost all certificates out there still based on RSA.
What's been removed from TLS 1.3 and is deprecated in TLS 1.2 (see RFC 7525) is the RSA *handshake*, as opposed to "first use Diffie-Hellman to establish an encrypted connection, then authenticate with RSA".
I agree with Scott that people should be moving to ECDSA certificates, but unfortunately this has been slow going.