> threaten Silicon Valley's supremacy There was no inherent "supremacy", just one created by a bunch of companies being together. Did SV municipalities do anything else to deserve it? There are better places, with more rental space, more resources, better weather, and so on, plus WFH is here to stay...
I think this somewhat understates the strength of acquired advantages in agglomeration economies. Particularly in an economy of ideas it seems to me that acquired advantages account for most of the benefit; beyond "cheap rent" there's not much "inherent" advantage to be had.
Even in traditional industry many of the advantages are acquired (i.e. not geographic, which is what I think you're getting at with "inherent supremacy"), the textbook example being Lancashire's dominance in textiles in the 19th century (https://voxeu.org/article/agglomeration-explains-lancashire-...).
I think it's a reasonable point to suggest that the exodus from SV could accelerate the development of other startup/tech hubs, and weaken the comparative advantage of SV, but I think you may be understating the current strengths of SV by focusing on "original advantages" like rent and other environmental/geographic attributes.