The morning mail brought the letter as follows:

From June 30, it will be impossible to log in to Flickr photo hosting using a google or facebook account. Instead, the user is asked to create a Yahoo account.
It seems that Yahoo under the leadership of Marissa Mayer feels confident enough to throw a symbolic glove at once to two giants. But personally, it reminds me of a
story with Google+ - no matter how cool you are, imposing services on people is useless.