user-1: I am naively under the impression that just about anything can be a soft fork nowadays, and that this is one of the benefits of Segwit.  Also, it seems that many claim in order for Bitcoin Core to implement replay protection, a hard fork is required.  This seems contradictory.  Perhaps someone could correct any of these assumptions?

user38307: Replay protection is only needed in the case of a Hard Fork.
To understand why this is true you should first understand what HF and SF are.
A great answer on the difference of Soft or Hard Fork can be found here

-1: <p>I am naively under the impression that just about anything can be a soft fork nowadays, and that this is one of the benefits of Segwit.  Also, it seems that many claim in order for Bitcoin Core to implement replay protection, a hard fork is required.  This seems contradictory.  Perhaps someone could correct any of these assumptions?</p>
 38307: <p>Replay protection is only needed in the case of a <strong>Hard Fork</strong>.</p>

<p>To understand why this is true you should first understand what HF and SF are.</p>

<p>A great answer on the difference of Soft or Hard Fork can be found <a href="https://bitcoin.stackexchange.com/questions/30817/what-is-a-soft-fork">here</a></p>
