Indeed Unreal Engine is moving to Left-Up-Forward coordinates everywhere, starting with UEFN, and coming to UE5-6 in an incrementally-adoptable way through UI settings and C++ helper functions/macros to ease the transition. This will align Unreal with Y-Up, right handed standards of USD and glTF. Why? Because future 3d tools and ecosystems will be increasingly interoperable and standards-based. There are a lot of missing standards we’ll need to propose, and Team Unreal will be far more successful proposing new things if we adopt and add to existing standards and conventions. The USD-glTF-Maya-Houdini quadrant is the center of mass for complex code-art-pipeline tooling that is highly sensitive to coordinates. (Flipping coordinates when exporting from AutoCAD or Blender is easy enough; changing a movie vfx pipeline is not). Coordinates based on project settings sound like a have-it-your-way compromise but are a combinatorial mess when projects are a mix of code modules and content packages from many independent authors. The best time to make this change would have been 1995, but I believe the second best time is now with the launch of Scene Graph in UEFN.