OIN App update impact on existing installation

We are working on submitting version2 of our app on OIN. We are introducing a variable which admins will need to specify when installing the application. This variable will then be used to construct dynamic base URL to call our SCIM APIs. There is no other change in the app.
So existing version1 of the app uses SCIM base URL as https://admin.mindtickle.com/scim/v2
And version2 of the app will use https://scim.mindtickle.com/${app.subdomain}/scim/v2
where ${app.subdomain} is a tenant variable which will be required upon installation.

Q1. Before we proceed with submission we would like to understand the impact of this change on existing installations. Will they continue to work since we will support the static base URL of version1
Q2. How does migration/upgrade to version2 would work for our tenants. Are there any guidelines, documents on the process?