Fabs are expensive. Just keeping the fab in tip-top shapes will requires billions nowadays. Let alone building new fabs. Actually other than Samsung's NAND fab being built in Xi'an, China, I am not aware of major new fabs being built anywhere. Intel recently cancelled their planned Fab 42 in Arizona.
The simulation environments have become so advanced they are coming up with smaller design technique and it will surely be costly affair for foundries to consider those miniaturisation moulding in the physical chips.
@Kinnar, miniaturization is an interesting topic all around. The goal in electronics has always been smaller, faster, cheaper. However, the smaller piece of the equation is making things more difficult on a variety of fronts. For example, this miniaturization trend is making it challenging to reclaim components and materials from electronics as part of sustainability efforts. THe parts are so small that it's difficult both at teh start of the product life and at the end.