Gamers have two choices when buying Assassin's Creed Valhalla, and both of them will net a next-gen version. Buy the current-gen version for $49.99 on Amazon and get the free PS5/Xbox Series X upgrade, or buy the next-gen version for $59.99. Why wouldn't you just buy the current-gen version and technically get two games for $49.99? Why is Ubisoft even discounting the current-gen version and giving us a choice?

Ubisoft has confirmed Xbox One and PS4 copies of Assassin's Creed Valhalla will come with free upgrades to the Xbox Series X and PlayStation 5 versions that release alongside each next-gen console. Since both the PS5 and Xbox Series X are backwards compatible, you can buy the PS4 and Xbox One versions and play them on next-gen systems. This isn't the beefy next-gen optimized flavor, though, just the backwards compatible version. You can still take advantage of the full next-gen upgrade as well. So why even buy the next-gen only version for $59.99?

It's worth noting the digital version of AC Valhalla on Xbox One is $59.99, presumably because of Smart Delivery, which will automatically scale it to the next-gen version.
So in essence, Valhalla may have two different variants on next-gen consoles:
- Out-of-the-box backwards compatibility - You should be able to pop any BC game into either console and play them out of the box without having to upgrade the games. We're not sure if BC will work natively out of the box on PS5 or Xbox Series X, or if you'll have to download a patch for every BC game. We're also not sure if the BC patches will automatically upgrade said game on each console to their optimized versions. The Xbox Series X will do this with Smart Delivery, but we're not sure about the PS5.
- Next-gen optimized versions - These versions were built specifically to use each console's high-end specs, including the new Navi GPUs, Zen 2 CPUs for faster processing, dramatically boosted RAM pool, and the ultra-fast PCIe 4.0 SSDs that allow speedy fast-travel.
PS4, Xbox One disc copies will get you a free digital-only next-gen version of those respective games.
The reality is the next-gen version is, well, only for next-gen consoles. It comes optimized for those systems out of the gate and won't require any extra installs. If you buy a disc copy of Valhalla on PS4 or Xbox One, you'll have to re-download assets (or perhaps the entire game) in order to play the optimized version on that console.

If you buy the PS5/Xbox Series X version for $59.99, the game comes with everything you need for a next-gen experience.
Also, if you buy the PS4/Xbox One version, you'll have to hold onto the disc for rights management. The next-gen version won't play unless you put the PS4/Xbox One disc in.
So the extra $10 is more of a convenience thing and would give the game more value for trade-ins/secondhand sales. We're not sure how frictionless the current-to-next-gen upgrade path will be, and we're not sure how long the promotion lasts. It'll likely be limited just like the PS3 -> PS4 upgrade path that actually charged gamers $10.
Luckily you won't have to play for backwards compatibility. So if you just want to play the game at its base current-gen version, you can totally do so on Xbox Series X and PlayStation 5. You'll also be able to use your external HDD to boot because the current-gen flavor doesn't require the high-end PCIe 4.0 SSD to function.
The value proposition is aimed at current-gen gamers, for sure. They get two games for a price lower than a single next-gen game. But they also have to deal with the upgrade path situation and hold on to an older game disc that could depreciate over time, especially since the upgrade will be a one-time only use.