Yes, he did. There are multiple sources available for Ed Bastian's statements that DELTA would like to be be a launch customer for Boeing's NMA. ...
Sorry, but wrong again. For a senior executive at one of the world's largest publicly-traded companies, everything Ed Bastian says in public that is not off the record is to varying degrees "in official capacity" and "in official manner." Is it a legally-binding commitment? Clearly no, but it is a statement which signals interest and intent and could easily be seen as such by any reasonable person.
Bastian's has offered his services as an industry expert to comment on Boeing's woes, in exchange for free publicity for DL. Yes, he's said 'we're looking forward to being the launch customer' but he's also followed up on numerous occasions, as I've quoted above, by saying DL's interest is "premature" as the airplane doesn't exist in any form. And DL's mentioned more than once that it won't be able to make a decision on the NMA until it can properly evaluate the aircraft.
DL has already decided upon 49 additional A330/A350. The reason the entire 767 fleet doesn't have a replacement on order is because, at this moment in time, it's intending on extending the service life of its existing fleet -- there's 55 B767 that are about 22yo old or younger, including 29 that are 20yo or younger. Put simply, some of aircraft are either being replaced with the A330/A350 on order, but many of them are simply not up for replacement yet. When the time comes, DL will evaluate its options, and if the NMA is available and is the best fit, an order will come.
But the Boeing fanboys need to stop insisting that it's a done deal, because there's zero truth to that. It's an incredibly strong possibility that Boeing forecasts a limited market for the NMA, meaning its development costs will be projected into fewer aircraft, meaning that its best offer price to DL makes the acquisition unreasonable vs. acquiring A338, should DL desire a smaller widebody.