Sooner rather than later it'll be cheaper to buy a TwinScan system than to fix a PAS5500/750, but at that point why would the fab keep making 180nm chips when they can make more money making 45nm chips with the same system? Last I checked, some critical parts already had 1+ year lead times because they had to be made to order so fabs have to keep their own stock.
Edit: Sorry I misused "EOL" in a previous comment. They're still being supported my ASML, but you can't buy a new machine so expanding a fab means upgrading the node.