What do the new rules for private apps on Shopify mean for existing installations?

[johnyjohny]

Shopify new rules say that custom and private applications are intended for individual merchant use only (including all stores owned by a single merchant). Distribution of apps to multiple merchants is only permitted for public apps.

I have 2 questions:

1. What that means for existing installations. Will existing installations continue working?
2. I was testing some app on my dev store and I see that it is still possible to install private even if this app has been installed on multiple stores before. Does that mean it is still possible to install it and the rule will be applied with some delay? What can happen if merchant install private app that has been installed also in other stores?

Thank you