Unless the employee leaves for a role (more senior, more pay, and/or more responsibilities) which at his/her current company simply isn't available or feasible.
I have experienced this from both ends, as the employee who outgrew my current role, and as a manager who my direct report outgrew their role. In this case, apart from trying to create a similar role (which often than not is impossible), the best you can do is to wish them the best, and be proud of the fact that you've worked with such an awesome colleague that they have now surpassed what the role could do for them. :)
This, exactly. I left a great company because I was at the top of the (small) technology department and didn't see any chance for further technical career development, either in management or in technology. It didn't make sense for the company to radically change their technical direction nor to hire a larger team.
At least that was my assessment. Nine months after I left they spun off a small start-up that, if I had known was coming, would have made me more likely to stay.
I have experienced this from both ends, as the employee who outgrew my current role, and as a manager who my direct report outgrew their role. In this case, apart from trying to create a similar role (which often than not is impossible), the best you can do is to wish them the best, and be proud of the fact that you've worked with such an awesome colleague that they have now surpassed what the role could do for them. :)