Logistics is the science of project and project support. Failure statistics that provide information about potential failures may be utilized to determine required availability of spare parts.
To support projects, especially when dealing with personal computers, I buy compatible parts for as long as possible so most parts are interchangeable. This can keep computers running for a longer number of years (if desired in spite of obsolescence). I consider the technologies of most computers today to have useful lifetimes as workstations for the forseeable future.