Not really a suprise that the 50th Anniversary will feature these villians. Spoilers http://www.bbc.co.uk/news/entertainment-arts-23398212
The sybols in the background look very Gallifreyan - will we be seeing the end of the Time War seeing what will probably turn out to be John Hurt's Doctor ending the Time War by destroying both species?
Not necessarily the end of the War. The Comic-Con trailer shows Time Lords and Daleks engaged in battle, presumably this is just some random battle taking place at any point in the Time War.
Honestly, I would've been surprised if they hadn't appeared. Besides, it was pretty much a given considering the speculation in regards to the John Hurt Doctor.