You won't be able to stubbornly cling to the old Google+ Photos much longer (assuming people are doing that). The official Google+ account has confirmed that August 1st is the shutdown date for Google+ Photos. It won't be a huge adjustment for most users—the new Google Photos already has all your stuff stored and organized.
The shutdown will happen in stages starting on August 1st. The Android app will be the first to go. You'll have no choice but to update Google+ and download the new Photos app if you want to continue backing up and managing your content on Android. In the days and weeks following this, the web and iOS versions of Google+ Photos will stop working as well.
This is just changing the way you access your photos on Google's servers. All the files are still in the same place, you'll just be using the new Photos app and website to see them.