TCP remains for cases where speed is required so TLS is skipped. Instead of application layers, I'd assume evolution on transport layers, so next to plaintext

TCP remains for cases where speed is required so TLS is skipped. Instead of application layers, I'd assume evolution on transport layers, so next to plaintext TCP there would be less reliable faster transport protocol, secure but slower transport protocol and possibly others. Similarly, is UDP a zero cost layer? If not, one could perhaps get more speed from working directly with IP.