Moffat (who didn't write that particular DWM news item) has certainly worked to create the impression that there is unannounced casting. Which there probably is... like Freema Agyeman and Noel Clarke, who both tweeted photographs of the two of them together, during the timeframe when the special was being shot. This just after Agyeman had tweeted "off to play with old friends."
You never know what they've got planned. But either way, there will be rumors of classic Doctors in the special up until the moment it's finished airing, because people never give up hope.