On February 12,2016, Head of Google Photos, Anil Sabharwal announced the end of Picasa.
Moving on from Picasa
Since the launch of Google Photos, we’ve had a lot of questions around what this means for the future of Picasa. After much thought and consideration, we’ve decided to retire Picasa over the coming months in order to focus entirely on a single photo service in Google Photos. We believe we can create a much better experience by focusing on one service that provides more functionality and works across mobile and desktop, rather than divide our efforts across two different products.
For those who have photos and videos in a Picasa Web Album…
…the easiest way to still access, modify and share most of that content is to log in to Google Photos, and all your photos and videos will already be there. Using Google Photos, you can continue to upload and organize your memories, as well as enjoy other great benefits like better ways to search and share your images.
These changes are effective from May 1, 2016. Also, Picasa desktop application will no longer be supported by Google by March 15, 2016. 
All roads lead to Google Photos.