At Google I/O 2017 today, Google announced the launch of "Suggestive Sharing". This is a feature designed to improve the sharing ability of Google Photos. The way the service works is instead of having to select certain photos and share them manually, the new feature will allows users to automatically share photos taken with assigned contacts and these contacts will be suggested to you by Google's machine learning technology.
As part of today's announcement, Google also announced "Shared Libraries." The way this feature works is once a person has been approved to see certain image categories, that person will also be able to receive new images as and when they are taken. In short, not only will they be accessible via the image taker's Google Photos catalog, but also as part of the assigned person's Google Photos catalog. This of course works both ways as well. So once someone else has assigned you as a 'partner' in the sharing process, you will have access to new images taken by the other person, as soon as they have taken the images. No manual sharing needed, ever. All the images taken that you want to share with the mentioned person, will always automatically be shared with them – as if they had taken the pictures.
In terms of when you can expect the feature to go live, Google has confirmed that the features (both Suggesting Sharing and Shared Libraries) will be available to all Android users in the coming weeks. This marks a fairly big expansion of Google Photos capabilities and in such a short space of time. It was exactly two years ago at Google I/O 2017 when Google Photos was first introduced and become available. Today's update represents how far the app and service has come in such a short space. Google further highlighted just how prevalent Google Photos now is, as during today's event Google confirmed that Photos now has 500 million monthly active users and sees as much as 1.2 billion photos/videos being uploaded each day. Now of course, not only will your Google Photos account be your account, but also anyone's else's that you want it to be.