The Delta 767 was probably there for temporary storage. A lot of airlines are temporarily storing jets due to the US economic downturn. I think it is a fair bet that the airplane will be back in service in less than a few months.
As for the 732s and 733s, I really couldn't answer. It is my thought that the 732s are probably gone for good.
Give me a break, I created this username when I was a kid...