We work in 2 weeks sprints, using the SCRUM methodology.
There is interest from our external stakeholders in our Advanced Roadmap to represent the Design, Implementation phases.
Our User Stories are really Dev Tasks currently, and Epics are the top level defined story from Product.
I can certainly have a set of Stories for the 'design' of various components and services and just assign them to a release as a milestone.
I believe our stake holders are concerned with the current Design, and next phase implementation and want to know when we will have a better sense for the remaining implementation.