WotLK: And the Ressurection of Daggers?Follow

As for the question "will they perform in PvE solo", that depends on what you call 'perform'. I've been daggers 1 'till 70 and didn't have any problems with it. 'Course the hardcores here will tell you how much better combat is for leveling, etc. I don't suspect that to change, since the main 'dagger resurrection talent' (Slaughter from the Shadows) is so far up the subtlety tree you'll have to be at least level 59 before you can get the full benefit of the talent. As for grinding, I've always preferred subtlety/daggers above any form of combat. The immense burst is actually useful against non-elite mobs and I rip trough the avarage level 70 mob in seconds.

As for PvP, it remains to be seen. But seeing as how Subtlety is primarily a PvP tree and Slaughter from the Shadows is located in that tree, I reckon daggers have a fairly good chance. Subtlety non-daggers will on the other hand still be a viable; you'll want to go up the subtlety tree until shadowstep and pick Seal Fate to go along with it.

As for raiding... Who knows? Subtlety daggers will probably be a big no-no... Mutilate/combat daggers might end up being on par with combat swords, but it's really too early to tell.

In the end, I reckon daggers will have a pretty good chance of being useful, or at least lifted off the point where every rogue in the game akknowledges them as badly inferior.