Epic Games is already working towards Unreal Engine 6 – the next big iteration of its game creation toolkit – which is expected to be "several years" away.
In an interview with The Verge, Epic's CEO, Tim Sweeney, refers to the power of the company's "high-end" engine, but also the "ease of use" of Unreal Editor for Fortnite (simplified tools players can use to make creative mode maps in the hit battle royale). He explains: "The real power will come when we bring these two worlds together so we have the entire power of our high-end game engine merged with the ease of use that we put together in [Unreal Editor for Fortnite]. That's going to take several years. And when that process is complete, that will be Unreal Engine 6."
Sweeney explains that the idea for Unreal Engine 6 is that devs can simply "build an app once" and then be able to roll it out "as a standalone game for any platform," with the option to put their work into any game that also chooses to "use this technology base." That includes Fortnite, for example – content would evidently be interoperable, able to be used across different spaces that use Unreal Engine 6, seemingly.
Apparently, we've already been given a bit of an example of this with the "persistent universe" that Disney and Epic Games are cooking up in Fortnite. It's still not completely clear what this universe actually is, but Sweeney describes it as a "Disney ecosystem" that "fully interoperates with the Fortnite ecosystem." Enter Unreal Engine 6, and "that's going to make that possible for everybody," indie and AAA developers alike, Sweeney says.
Much of this vision is still, frankly, rather primordial and hard to decipher at this point, but Epic clearly has a lot of ideas in its tank. It'll be interesting to see how game development may change when Unreal Engine 6 actually arrives.