https://blog.playstation.com/2024/09/24/horizon-zero-dawn-remastered-is-coming-to-ps5-pc-october-31-2024/

Horizon Zero Dawn Remastered features over 10 hours of re-recorded conversation, mocap and countless graphical improvements that bring the game to the same visual fidelity as its critically acclaimed sequel Horizon Forbidden West. [...] The story’s many compelling characters have been upgraded, bringing them in line with current generation advances in character models and rendering.
The audio experience in Horizon Zero Dawn Remastered has been significantly enhanced. We’ve completely revamped the sound mix, now supporting PS5 Tempest 3D Audio Tech2 for higher-order ambisonics and Atmos rendering for an immersive soundscape. Our sound design has also seen major improvements, with hundreds of improvements both in-game and in the cinematics.
[...] We’ve integrated custom haptics for the DualSense controller throughout the game, providing tactile feedback that heightens immersion. Additionally, we’ve introduced a new optional accessibility feature that utilizes sound and haptic feedback to notify players of interactable elements, such as pickups, that were previously only indicated visually.
[...] The PC version (Account for PlayStation Network required on PC) on Windows includes the PlayStation overlay with Trophy support and has its own set of features, such as support for ultra-wide resolutions and the latest performance enhancing technologies like NVIDIA DLSS 3 and AMD FSR 3.1 with frame generation. [...]
Many of the accessibility features that were first introduced in Horizon Forbidden West have been included for this Remastered version as well; remappable controls, haptic cues, and various assist toggles will enable all players to fully enjoy the game.
For those that have already played it, we’ve made sure that your old save games will work; [...]
For existing owners of Horizon Zero Dawn (PS4, PC) and/or Horizon Zero Dawn Complete Edition (PS4, PS5, PC): you can upgrade to the digital version of Horizon Zero Dawn Remastered for $9.99 on both PlayStation 5 console and on PC (via Steam or Epic Game Store). This includes fans who added the game to their libraries during PlayStation’s Play At Home initiative.
Owners of the Horizon Zero Dawn PS4 game disc can access this offer by inserting the game disc into their PS5 console (and will need to keep the disc inserted each time to play the game).
[...]PS4 game disc owners who buy the PS5 Digital Edition disc-free console will not be able to access the upgrade offer.
For new fans, the game can be purchased for $49.99 on PlayStation Store, Steam, or Epic Game Store. You will receive the Horizon Zero Dawn Complete Edition.

Emphasis is mine.

This is just a glorified update, not a remaster. For the most part, it's a cashgrab and I would be hard pressed to justify the full price point they are asking for this thing. At least they are offering the update at a discount for existing customers.

But it's hilarious that the existing customers who bought the game physically and then bought their new flagship console apparently are not entitled to the discount. I don't understand if Sony just doesn't care about the PS5 Pro and its users, or they think that people will buy the console + external disc tray for this?

Oh, and now the game requires a PSN account on PC as well, and they only mentioned Steam and Epic Store despite the game being also released on GoG.