Amazon still runs a bunch of Perl in the back. Just because you're stuck with some design choice doesn't mean that framework has a solid future. People still write plenty of COBOL but you don't see any new applications using it
Plenty of new mainframe code is written in corporate settings. Legacy modernization is strong as ever and for some companies that doesn’t mean moving off mainframe - it means upgrading, cleaning up and cloning legacy COBOL code bases and some times writing new.