It depends on your goals as an organization paired with each team members career goals. Are you attempting to give them a map that is suitable in consulting, enterprise, startups or just a generalized roadmap? You are here (x) role today and would like to be there (z) in a specific amount of time. I think many people get frustrated with consulting work so they have a tendency to go client side (whether start up or enterprise). I think you should be transparent and accept that as reality and map several paths both internally and externally. I think that would benefit your organization culturally and reduce churn. Incorporate existing technical/business skills and map each of those tracks out, showing how they are beneficial to the consultant/developer over the course of their career. Just a few thoughts.

You could think about skills development in a T-shape form where your employees can acquire more depth in their skillset or go broad.

More depth would mean developing their technical ability, going from junior developer to architect of smaller size applications to massive applications or developing mastery in certain technologies.

More breadth would mean providing them with a path that lets them develop their managerial skills, technical or non-technical, eventually equipping them with skills to run their own technical teams, driving sales, become partners in the business, etc.

A consideration would also be to have an honest conversation with your team and where do they want to grow their careers. Though they might churn to startups or enterprise companies, treating them well could result in referral business.