What happens to Master-Detail after deleting (Managed Package)

Question

When I delete a Master-Detail relationship in my managed Package

1. Will it be replaced by a Lookup, like this Knowledge arcticle says?
2. Will there still be a Master-Detail relationship in our customers org, after upgrading, So it has to be deleted by admins? like this ISVforce Guide tells us.
3. Will it be totally removed everywhere? As according to this Idea there can be no MD-relationships on managed objects in foreign orgs.
4. Something else?

Answer 1

The Master-Detail relationship (like any managed custom field) will not be deleted in the customer (subscriber) organisations, like stated in the ISV guide (2).

Instead it will be listed as 'unused component' under the package components settings after the upgrade to the new package version (without the Master-Detail relationship) was applied.

At this point an admin of an specific subscriber organisation is able to delete the Master-Detail relationship (assumed the relationship is not used by other components/integrations). The deletion now is like for an unmanaged Master-Detail relationship with all the consequences described in the knowledge article (1).