Neither plane is going anywhere anytime soon.

The A319s and A320s (especially the A319s) will allow Delta to right-size several markets, especially on transcons. They might be the plane that allow routes such as LAX-JAX, LAX-RDU, LAX-BDL and LAX-CMH to come back, as the 737-800s were too much plane there, but the A319s are a good bit smaller. Same out of SLC (a good number of A319/A320s are moving to SLC this Spring, freeing up MD-90s to go to MSP). There are plans in the works to get IFE and wi-fi on all A319s and A320s over the next few years.

Neither the 767-300s (which are the bad 767s - Delta's 767-400s compare quite well to the A330s) or the A330s are going anywhere soon either. Delta is installing true flat beds (the same as the ones on the 767-400s to Heathrow) on these planes in BusinessElite, and installing PTVs/AVOD in every seat in economy.

Also, keep in mind the 767-300s and A330s serve very different missions. The 763 seats around 216 people; the A330-300 is 298. The A330-300 shines in markets where a lower CASM is needed - the A330 will become the primary plane to some of those heavy leisure markets that can easily fill up the back of the plane. The A330-200 and 767-400 have similar capacities, but the A330-200 has a bit more range, making it a better choice to keep on Pacific routes (and potentially longer TATL routes) while keeping the 767-400 on Europe routes.