Sony’s controversial PlayStation Network requirement for its PC games is once again in the spotlight after the company delisted the original Horizon Zero Dawn on Steam and the Epic Games Store and added the PSN requirement to the upcoming single-player remaster.
This is not true in the literal sense.
You cannot redeem HZD keys, and buy it as part of a bundle with both versions. They stopped selling it standalone.
So you can get the upgrade for $10 if you already have it, or wait for a sale on the bundle.
But in either case you can still play the original release without the PSN requirement even if bought after the remaster release.