CRLF is obsolete and should be abolished

Changing the line endings can invalidate signatures over plaintext content. So an email MTA, for example, could never do so. Nor most proxy implementations. Then there's the high latent potential for request smuggling, command injection, and privilege escalation, via careful crafting of ambiguous header lines or protocol commands that target less robust implementations. With some protocols, it may cause declared content sizes to be incorrect, leading to bizarre hangs, which is to say, another attack surface.

In practice, retiring CRLF can't be safely performed unilaterally or by fiat, we'll need to devise a whole new handshake to affirm that both ends are on the same page re. newline semantics.