According to Wiki, there have been 965 767s built as of June 2008, and 550 Airbus A330s as of June 2008. With orders still to be filled, the Airbus will be close to the 767 numbers by the time both aircraft are officially out of production.
Also in the A330s favor is the limited commonality with the A340.
There are much more 757 left than A340 but cannibalization is last possibility then support for commercial fleet is stalled.
I guess normal support for A330 will proceed 10 years longer than for 767. We'll see how Air Force will take that into account.
A KC-45 fleet can profit from improvements for ongoing A330 production like the now offered new engines PW4000-100 Advantage70 or GEnX. Will there be any commercial improvements for 767?
Orders for 767 this year so far: Zero
http://active.boeing.com/commercial/orders/index.cfm