A Statement was recently released on Anna Netrebko's page:
"I am so sorry to have to withdraw from the role of Marguerite in Faust. After much consideration and intensive preparation, I have come to the conclusion that the role is not right for me. I had been very much looking forward to debuting this role at the Royal Opera House and following it with further performances in Vienna and Baden-Baden. Unfortunately, I must now withdraw from all these productions. I am very sad to be disappointing my fans in these cities and hope they will understand the difficult decision that I have had to make. However, I am very much looking forward to returning to The Royal Opera to perform with the company again in 2015."
The soprano was to have to made her role debut at the ROH and was later to have sung two more runs. There have been no replacements of yet but the companies are working hard to find a new soprano.