Q: Migrating from a single shared id to family sharing

We have been an iOS family for many years and we have always used my personal apple id for app store purchases, the same id I use for iCloud, which means my wife and kids all have access to my apple id information.  It's not a crisis but as the kids get older and start to do more things on their own it's time to start to separate our accounts.  Each member of my family has their own apple id which they use for backups, etc.

If I move to Family Sharing what happens to the apps that everyone currently has on their apple devices that are associated with my account?  Will they disappear?  Will this work?  Is it seamless?