Certainly chemistry on a team that seems to be playing well above expectations is one concern
The other: brewers are in rare territory for the org this late in the season. Even if they have more talent on a future team, there is no guarantee that will translate vs future injuries and competition (see dodgers).
I just think they will regret keeping an overloaded farm system on an org poised for a deep playoff run, while competitors make their moves. We are seeing the impact a bat like Vaughn has been swinging on this lineup.