How realistic is a career change at 40+?

Very realistic — with the right strategy. The German labour market is suffering from a skills shortage, and many companies are explicitly seeking experienced career changers. Success factors: a clear target role (not 'anything different'), proven transferable skills, concrete measures (certificate, project, network in target industry). Realistic expectations: 6-12 months search time and possibly a salary reduction of 10-20% in the first transitional step.