The Peter Principle argues that everybody is ultimately promoted to their level of incomptence. Holmgren seems to actively seek his out. He's a great coach; he's done nothing to indicate that he belongs on the business side of an NFL franchise. In Seattle he wore both hats, with mixed results(No championship, one Super Bowl loss).
This might be Holmgren's last job. If it isn't, the next one should have him roaming the sidelines.