It is impossible to say with certainty that any particular technical challenge will never be overcome. Human beings are amazingly ingenious and technology in particular continues to move forward at a dizzying rate.
That said, there are no known algorithms that will allow 3D modeling operations to be efficiently multithreaded. This is true in SketchUp as well as in all of the major 3D CAD modeling kernels (ACIS, Parasolid, etc.). Some operations outside the kernel can be accelerated, but not in the way you’re thinking.
It is a simple and well-understood axiom that time = money and anything that can minimize the time you spend waiting for your computer to finish some task will increase the profitability of your business. We understand that on the SketchUp team and we’re always working to make SketchUp faster.
But multithreading on the CPU just isn’t the best way to do it at this time. SketchUp is much more dependent on GPU performance than CPU. Splashing out on a hot NVIDIA 1080ti graphics card will improve your SketchUp performance much more than extra cores in your CPU.