I went through the thread in the UD Forum. For those who see the same warning and see this thread you can go through the full UD Forum thread or just read the below post form the ISY Integration Lead Developer. Short answer is you may have a little work to do because the changes in the ISY integration will affect some of the entities and services with the IS , but the end state will be more capability in HA being able to access more of the Insteon devices capabilities.
I wanted to provide one last update to this thread. I use my ISY to control my Insteon devices. I don’t use any of the other features of the ISY (I have moved everything else to HA). I do use Insteon events (DON, DOF etc.) to create timers etc. and I do have some scenes setup in the ISY and control them from Insteon.
I took the plunge and removed the entries in configuration.yaml that were there to establish the connection to the ISY itself (38 Insteon devices, so it it was going to required manual changes it would have been a lot of work). Upon restart, everything worked with no need to any manual work and the warning went away. So it was as seamless as “shbatm” indicated it would be for my configuration.