Google's Borg clusters don't have wildly larger sizes than that despite having more years of development and a lot of motivation at that scale. They instead hav

Google's Borg clusters don't have wildly larger sizes than that despite having more years of development and a lot of motivation at that scale. They instead have a lot of clusters and transparent inter-cluster network topologies (i.e. you can choose clusters with very high bandwidths to each other). The fundamental design just isn't infinitely scalable, and at a certain point, you might rather have some bulkheads/autonomy or regional diversity.