If you want to know the future of any game engine, look at what NVidia + Microsoft does. Anything else for engine developers, when the matter is core tech, is irrelevant.
UE5 will only exist after DirectX12 is obsolete which may be over a decade from now.
And no, DX or OpenGL developers would never ditch technology based on triangles, that doesn’t make sense. Decades of R&D were spent to create an ocean of code and hardware optimized to render triangles.