I’m glad you’ve been successful enough here to have to make such a tough call 😄
I put myself right in your shoes as I was reading. People rely upon you and it’s hard for them to find someone to rely upon so they like you to stick around. For me it’s patients who know I’ll be available and they can trust me to be non-judgmental and efficient. It’s not trivial to replace well done services. The fact they stuck around for 10 years is proof that you were available, efficient and great to work with. Maybe your change will cause them to step outside their comfort zones also and make changes? We never know the knock on effects of our actions, right? But mostly we have to be responsible for our changes and let folk be responsible for theirs (even where our moves create changes for them).
Hard to let go, especially when work based relationships left behind don’t have a foothold elsewhere in your life.

‘Progress’ needs your input more though 😄.