First of all a seven hour delay, well those things happen.
I was delayed once for 14 hours because a brandnew Transavia B757 was having engine problems and no replacement aircraft was available.
so we can't blame that on the poor status of the 10's.
however, I think the DC10's must go due to the fact they are beginning to become a bad image for NW.
this because all other airlines already fly new aircraft such as the 777. yet NW is the only airline not to follow in the near future, yes i know about the new 757's and 330's. but they wont start arriving for another year maybe 2.