I think the corner cases are likely hard, but the fundamental mathematical representations of the 3D geometry haven't changed. If the licensing cost of Parasolid and ASICs is reasonable, there isn't really a commercial incentive to create something new from scratch. The current market trend is consolidation as Autodesk and Hexagon when on a buying spree and bought up a lot of CAD and CAM software.

OpenCASCADE used to be commercial, but they couldn't find enough customers to keep on and it got open sourced after a failed commercial existence.