ROLLING OUT: SharePoint Online team sites + Office 365 Groups & Pages

Corrected (ignore my question - I see Tejas Mehta answered the question officially for permissions and groups/SharePoint sites). 

Copying here as it never hurts to be written twice:

"SharePoint does provide the ability for Site Owners to specify different permissions on resources. Office 365 Groups promises a permission model whereby all group members have access to the group’s resources across workloads (e.g. conversations, files, notebook, etc.). To deliver consistency, SharePoint site collections associated with a Group will also follow this model. So, a group (site) owner can add new permission levels and assign to new users or groups on a resource, but would not be able to remove the permission levels assigned to the group’s owners or members. We are working on delivering a new permissions management UX that will allow for group (site) owners to change the group members’ permission level from Edit to Read-only (and vice versa) but you would not be able to remove the members from resources in the SharePoint site collection."