I think it's a fake rumour. I just can't imagine her changing her name. The Sharapova name is a brand and even changing it for a week or two would be ridiculous. And i think the fact she hasnt released a statement yet means that they probably think it's good publicity and it can help increase the sales.
Now speaking from a fan's perspective and somebody who doesn't care about Maria's off court activities, let alone that sugarpova BS, I must say that if it's true then she's completely lost it