It is now confirmed that Google is shutting down Picasa service starting March 2016. After the launch of Google Photos a lot of people already knew this would happen eventually in order to focus entirely on a single photo service in Google Photos. For those who do not know about Picasa, Picasa is a photo-sharing and storing website that’s been in Google’s lineup since 2004.
According to Google Picasa Blog:

"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."

When Google launched Google Photos in May 2015, backed by deep neural network-driven image recognition (used to automate photo organization without user-applied tags) and free unlimited storage for high-def photos and video, Google Photos looked and sounded great. And icing on the cake is its availability to users of both Android and iOS.

"Google Photos gives you a single, private place to keep a lifetime of memories, and access them from any device. They’re automatically backed up and synced, so you can have peace of mind that your photos are safe, available across all your devices.
And when we say a lifetime of memories, we really mean it. With Google Photos, you can now back up and store unlimited, high-quality photos and videos, for free. We maintain the original resolution up to 16 MP for photos, and 1080p high-definition for videos, and store compressed versions of the photos and videos in beautiful, print-quality resolution."

So now, Google Picasa is gone, one obvious question to ask is whether there will be an API for Google Photos. After all, there’s one for Google Picasa. The company has not confirmed it yet, According to a company spokeswoman “No current plans for an API, but this is just v1 of the Photos app. There is definitely more to come.”
So what are Picasa users to do now that their photo service is getting shut down? Google is unsurprisingly telling folks to move over to Google Photos, the company’s new-and-improved photo service. According to Google:

Beginning May 1st, 2016, we’ll start rolling out changes to the Picasa Web Albums Data API and no longer support the following functionality:
 - Flash support
 - Community search
 - Mutation operations other than uploads
 - All support for tags, comments, and contacts
The API will still support other functions, including reading photos, reading albums, reading photos in albums, and uploading new photos. Although these operations will continue to be supported and the protocol will remain the same, the content included in the responses and the operation behavior may change.

So, It is now making perfect sense that there will be an API soon for developers to work with the Google Photos, as with no API (yet), why might Google’s Photos announcement be relevant to developers now? And it is worth mentioning here that developers have always been the key to ecosystem dominance.
We can sense the heat between Google and Apple and Google has dramatically turned it up by offering free unlimited storage of high-def images and video. And Google is playing this game very patiently. Google is saying, “You are free to choose between Android and iOS. It does not matter whether you take pictures or shoot videos on iOS, just store them with us for FREE”. By doing so Google is increasing the chances of adoption by Apple users.
Google will do its best to deliver a seamless experience on both platforms, but the chances are that it will be a better experience on Android. Google’s sphere of influence will expand and, as a result, more developers will be drawn to it like moths to light. Even if developers start by building iOS apps that work with the Google Photos API. It’s not available yet. But it will be, and when it is, that’ll be just another foot in the door. Eventually, some users of Google Photos on iOS will be compelled to move.