http://www.bigfinish.com/news/v/doctor-who-50th-anniversary-release-announced

Oh shit! There's going to be a multi-doctor Anniversary story... but not what you're thinking. This one's going to be on CDs!

All surviving classic Doctors - Tom Baker, Peter Davison, Colin Baker, Sylvester McCoy and Paul McGann - will star in Big Finish's The Light at the End, a 2-disc adventure where The Doctor's paths cross with each other as they face, of course, their imminent destruction!

Also hopping along for the fun will be a companion for each Doctor - Tom getting Louise Jameson's Leela, Peter, Sarah Sutton as Nyssa, Nicola Bryant returning as Peri with Colin, Sophie Aldred as Ace for Sylvester, and Paul McGann will have Charley, India Fisher's companion character from the first Eighth Doctor audios.

The story, also featuring the return of Geoffrey Beevers as The Master, is due for release in November.