We are at a point where the limiting factor is the distance between the components. That’s why we can see a trend to SoC computers. The problem is that you are no longer able to upgrade single components.
That's true. The idea behind this trend towards system-on-chip (SoC) computers is to pack everything on one chip, including the CPU and GPU, which means there is less space between components and less need for upgrades. However, it also means that you may be stuck with what your computer comes with. It's still possible to upgrade certain things like RAM or storage, but not as easily as before when we could replace individual components.