Rumour 2 - Next Pinball to be released by Stern was thought to be Avengers but now suggestions are that it could be X-men.
Personally I like the idea of Avengers because it would line up with the movie and there could be lots of cool features.
http://pinside.com/pinball/forum/topic/sterns-2012-pin-releases-whats-after-acdc
Either theme works for me! 
I am hoping for a Avengers myself (like a monster bash type machine with all the different characters from other shows, etc - would be awesome also license might be cheaper as not a mega hit at the movies yet ???? my theory is wild guessing
