Answer
That depends on business process fit, customization debt, integration pressure, staffing, and how much disruption the organization can tolerate. Many IBM i teams should evaluate phased modernization or extension before assuming replacement is the only path, but the answer is never purely technical.
Buyers should compare which parts of the current ERP still create value, which parts create friction, and what the business can realistically absorb in terms of change. A full replacement may be right, but it should follow documented process and risk analysis rather than frustration alone.