I'm actually a little concerned about this for the MCU. Maybe not so much for the established characters, but for the X-men and FF4.
However I'm hoping this means a few things:
1) Kevin has amassed a creative team that understands the source material and how to use it.
2) He is leaving a competent day to day successor in place with some fanboy-ish leanings at Marvel Studios
3) There is a long term plan in place at Marvel Studios
4) He still gets to read and comment on things to ensure a level of quality.
As for Star Wars I can't fault the guy. For a lot of us that would be a dream job and they need help. I'm guessing his initial input will be added to help right the ship, and provide the long term planning , fan understanding, and continuity aspects which seem to have been missing from the current trilogy. If I was a Star Wars fan, I would see this as a good thing, and hope Kevin does a Knights of the Old Republic / Ancient Jedi thing as his first film.