The ONE thing people want to know more than anything
"How is this going to affect me?"
That's what they wonder.
How well you can address that question as early and as clearly as possible makes the difference in how well any transition will go, large or small.
Incidentally, if you ARE the leader, you also have this question on your mind. Anytime a follower makes a shift, you wonder, "how is this going to affect me?" The only difference is, you're the one who has the responsibility of solving or fixing whatever may occur as a result of whatever it is that they do, or don't do.
Everybody has the same question, the only difference is one person has a different level of responsibility.