TypeScript 6.0 Ends Permissive Defaults, Forces Ecosystem-Wide Modernization

TypeScript 6.0 marks a forced industry modernization—70% of existing codebases will encounter breaking compiler changes, making migration mandatory rather than optional. By enforcing strict mode by default and dropping ES5 support, TypeScript is declaring that backward compatibility no longer justifies its cost, accelerating ecosystem-wide adoption of modern JavaScript standards and fundamentally reshaping CI/CD pipelines for most development teams.