The Mac Pro tower has not been updated for quite a few years (as of June, 2012) and a lot of people wonder if it will be discontinued.
One of Apples web pages explaining Thuderbolt may have shown a hint of what is to come. Look at the text carefully that follows. “With Thunderbolt, you’re just as likely to build a professional video setup around your MacBook Pro or iMac as your Mac Pro.” Notice the words “iMac as your Mac Pro”. Might this not suggest that Apple has already planned to do away with the tower?
A counter argument has appeared on the Internet, macpro.MacRumors that a new Mac Pro will indeed come out in 2013.
http://macpro.macrumors.com/. If this article fails to show then search for Mac Pro Rumors (Tuesday June 12, 2012) or “Apple Spokesperson Confirms New Mac Pro Design Likely Coming in 2013”.