Answer
Yes. Many strong IBM i modernization programs keep the core ERP in place while improving the layers around it first ... user experience, workflow automation, API access, reporting, and selected code areas that are blocking change. That phased approach usually lowers risk because it preserves the transaction engine the business already trusts.
Buyers should still be explicit about the target outcome for each phase. Modernization works best when each step solves a defined business bottleneck instead of trying to make the whole environment feel newer all at once.