They did say they would be releasing to all consoles simultaneously. That might mean waiting for the PSN problems to be resolved, which might mean waiting.
That's been my prediction, but I'm predicting the DLC won't be available until sometime in June. I believe the PSN will be down longer than anyone thinks, probably well into May. If Bethesda is truly committed to releasing the DLCs simultaneously then the PSN is holding it up. I bet Bethesda is waiting for Sony to figure out when all functions of the network will work again, before announcing anything about DLC.
If they aren't waiting on the PSN then the patches they just put out are probably holding it up too. Bethesda is going to let these new patches get some play time with the actual players of this game, to see if anymore bugs arise that need to be fixed before the DLC. They may keep an eye on things over the next week or two before making any announcements.
Sony is holding a press conference in Japan today. If no pertinent information about when the PSN is going to be back up, and Bethesda is really waiting for the PSN, then I wouldn't expect a trailer this week. Of course even if my prediction of the PSN being down well into May is correct, then we'll be waiting a while longer.
I don't care what is holding up a release I just want a trailer, and screen shots. Even if no official release date is given in the trailer, it would be something, to whet everyone's apetite.