The commercial problem
Experienced people may remain capable of contribution for years while job architecture, recruitment signals and professional identity continue to assume a shorter and more linear career.
The result is more than an individual employment problem. It is also a potential loss of productive capacity, income, entrepreneurship, mentoring, demand and organisational memory.
The design question
The useful question is not how to keep everyone in the same salaried role indefinitely. It is how accumulated capability can be identified, renewed where necessary, demonstrated, recognised and redeployed across employment, projects, advisory work, entrepreneurship and other viable forms.
Longer lives make experience more abundant. Existing commercial systems still make that experience too easy to strand.