It looks like a developer has managed to find some code within the master branch of Unreal Engine 4. Unreal Engine 4 version 4.14 released about a month ago, and it looks like digging around in the code reveals settings for Switch, SwitchConsole and SwitchHandheld.
Settings for SwitchHandheld appear to be fairly lower compared to SwitchConsole, which in turn are a notch lower than Unreal Engine 4 defaults on PS4, Xbox One, and PC. Speaking on NeoGAF, the developer said that “the SwitchConsole settings are a notch lower than the UE4 defaults used on PC, PS4 and XB1,” and that they serve as “a good starting point to get a PS4/XB1 UE4 game to run acceptably on the Switch,” which should be encouraging news to those hoping for third party support on the next Nintendo system.
We already know most third parties are enthusiastic about Switch support, though the particulars about what kinds of games we can expect are, naturally, not known right now- hopefully all is made clear by January 12, when Nintendo take the wraps off of the Switch entirely.
[Thanks Nintendo Everything!]