I cannot find a source for this outside of HN, but I have read here that R&D costs to build the next generations fabrication plants double each iteration which

I cannot find a source for this outside of HN, but I have read here that R&D costs to build the next generations fabrication plants double each iteration which limits the total number of sustainable independent chipmakers. Currently, only 3 are left (TSMC, Samsung and Intel) and they all might give up within a few generations when it gets too expensive to scale down further.