If they wanted to, they could put faster flying mounts into the PS5 Horizon FW tomorrow with DLC. The two versions aren't dependent upon each other; the PS5 version could go way faster than the PS4 version if the developers so desired.
And, it would
suck...
As it is now with the flying mounts, you see the stitches of the world as the different biomes blend together. Even during the same ToD, the sky fades and the colors shift and the lighting changes and effects like fog rolls in as soon as you cross boundary barriers. Each area is custom-tuned for a certain cinematic presentation, with different foliage and weather and ambient sky and groundcover, and when you're walking between areas (particularly when you have to climb a mountain to get from one to the other,) the illusion that this is a seamless and sensible world works perfectly well; cross it from on high at high speed and the illusion has problems since structurally the zones need their own identity. The scale of the world feels big on foot, but in the sky, you see how far off from normal the size of the world is, as it goes from a misty jungle to an arid desert to a lush coastal forest in the span of five minutes.
Horizon is not a game made for flying. They put flying mounts in there because gamers griped that they couldn't fly, but flying usually sucks in games unless they're games made only for flying and it particularly sucks in open-world games for these reasons. (I'm very curious to see how flying works in Avatar Frontiers of Pandora, although they have an advantage in that they can fly amongst floating lands to keep it interesting, plus I don't believe they have confirmed a "fly-anywhere" mechanic.) Flying is fun when you're near the ground or flying through obstacles and fighting in the air; Horizon would have little reason to add obstacles in the air, and having dogfights with Sunwings would still be clumsy in fight mechanics (wing-to-wing melee combat?) and catastrophic to fail. So it makes sense why flight is only a bonus feature of the end of the game. It's possible that a third game could further expand the scale of the landscape so that flying over the entire world actually feels like flying (and isn't boring,) but the technical hurdles that a Horizon 3 wouldn't have to deal with in being PS5-exclusive would only partly solve the problems of flying sucking in Horizon.
Heh, it's always worth digging deeper into these "a developer said this..." memories that people have and take as gospel but never have a quote or link to really get into what the developer actually said. There's usually more to the story than people remember...
(I believe that line came from this
GDC Post-Mort with Guerrilla Games' Principle Artist Gilbert Sanders, where he talked about features which didn't make it into the first game, largely in familiar ways that features don't make it info first games of a series because of technical challenges or time difficulties or directorial choices that they couldn't get around in that previous game. Sometimes new hardware solves it, sometimes just better programming solves it, and sometimes they don't even bother to solve it because they didn't end up wanting to go in that direction anyway. It could also have come from the
Game AI NC event where they talked about having airborne creatures in Horizon, although that was primarily about solving for the Stormbird and other air-to-ground fighting enemies and adding height map elements to the game's open-world surface grid.)
For the record, you can glitch the game and fly over portions of the first Horizon and the HDD/CPU keeps up well enough. And then in Horizon FW, they added the Sunwing and did flying better. If they had done a third PS4 Horizon and they really cared about making flying work, probably they could have worked out the tech issues. It's similar to how GTA3 couldn't really do flying or seamless level transitions (except for the little Dodo, and I believe there's some old developer quote from back then about how the PS2's limitations made real flying not possible in that game) but by GTA San Andreas you can fly anywhere and don't hit loading screens. Given that a Horizon 3 would be only on PS5 (or PS5/PS6?), HDD would no longer be a problem, but again, the technical challenge is only part of the issue.
