When an organisation decides to modernise its IT infrastructure, new infrastructure is created and old infrastructure is decommissioned. Similarly with business infrastructure, when we modernise delivery with roles such as Product Owner and Scrum Master, older roles become obsolete and should be retired.
The roles of Product Owner and Scrum Master are defined in the Scrum Guide.  At a high level:
The responsibilities of these roles overlap with traditional management positions such as Solutions Manager, Project Manager and Project Administrator, while other responsibilities may be distributed or automated:
It is encumbent on organisations to identify impacts to organisational structure and roles when introducing Scrum. The roles of Product Owner and Scrum Master should be viewed as new roles and not retro-fitted into existing roles. Such appointments can impacts aspects such as governance, decision rights, reporting and the workforce itself.
It is common for organisations to appoint existing staff members in the roles of Product Owner and Scrum Master for various reasons. While this may be the quickest solution there are issues to be aware of. Staff may:
The organisation should take a holistic view to change and not only at the team level.
“Change is the only constant in life” — Heraclitus
Change Management is the application of a structured process and set of tools for leading the people side of change to achieve a desired outcome.  When an organisation seeks to adopt change, such as introducing agile practices, new opportunities are created while some may view change as a threat. Change Management requires the identification of the human impacts of change such that the organisation provides development opportunities for staff to perform new roles or for external staff to be hired.
Appropriate levels of communication, consultation and training should be planned for when introducing new practices and methods of work.