How about a copy and paste
Per the last dev stream. Its time stamped if you want to click on the link and listen to Dennis explain it yourself. While this is regards to UE5, it still applies to UE4 versions. They are able to backport some things to various degrees (not all things), and they have done so already. But you will not be seeing anything beyond 4.15
UE5 Update? (1:46:32):
Short answer: No. Not happening. No, it’s not easy. Still no. And no.
Long answer: The history of Unreal Engine, the UE3, UE4, UE5, those are the massive iterations in the fundamental structure of unreal changes where you are literally working with a different product. Unreal 3 is entirely separate from what Unreal 4 is. While Unreal 4’s foundation was built upon Unreal 3, their systems work architecturally differently.
Unreal Engine has different revision numbers, such as 4.5, 4.6, 4.25, etc. Those revision versions are similar, and they do get minor changes like performance upgrades, new tools to make new content, (which is often some of the biggest changes to Unreal Engine versions in that they offer things like new VFX tools or new animation tools, etc). Dennis says that by and large, those don’t affect things a ton in terms of delivering a fun game like Conan Exiles.
Conan Exiles was made in engine version 4.15, which is around 5 years old (it came out in February of 2017). When they started working on Conan Exiles, they had to do significant modifications to get it to work with their internal back end to get it to do everything that they needed. From character creation to server communication and many other systems. All those modifications have essentially locked them into Unreal Engine 4.15.
What they are able to do is take features from newer versions of Unreal and back port them to their Unreal Engine version of 4.15. Dennis made this clear, Conan Exiles will never be anything other than Unreal Engine 4.15 with heavy modifications. It is no longer possible to take the project, right click “Update Engine” and Select Unreal Engine 5.0. It is simply not that easy. Even if they tried, it would generate months of backlog work updating systems that they created for 4.15 to work with the changes that have happened to Unreal Engine 5.0
Once again, Dennis makes it clear. Conan Exiles will never be using Unreal Engine 5. As previously mentioned, they can take performance increases or specific tools and backport those to their version of Unreal Engine 4.15. Now if they ever decide to make something like a Conan Exiles 2, yes they will use whatever the most recent version of Unreal is available at the time.