I think it's obvious that Thunderbolt is not going to go very far. Look at the USB 3 market, and then look at the Thunderbolt market. Anything sold using thunderbolt costs like $400 and up, and even a 6 foot cable is $60. Seriously?
Just go for the 2012 if you plan on keeping it for two or more years. USB 3 is going to become mainstream, so why ruin it for yourself? Also, Ivy Bridge is quicker and cooler than Sandy Bridge from 2011. And when the next OSX (or OS11?) upgrade comes around, you might be cut short from all its features if you have the 2011 model, much like the whole AirPlay in Mountain Lion situation.
Just go for the 2012 if you plan on keeping it for two or more years. USB 3 is going to become mainstream, so why ruin it for yourself? Also, Ivy Bridge is quicker and cooler than Sandy Bridge from 2011. And when the next OSX (or OS11?) upgrade comes around, you might be cut short from all its features if you have the 2011 model, much like the whole AirPlay in Mountain Lion situation.