So seeing as they implemented new quests into the old world dungeons I decided to see just how much they've changed and I must say I was very impressed with the story behind some of them and how they explain the reasoning for some bosses not being dead(i.e. Balnazzar). So I decided to head into Stratholme(being a W3 fan) and see what was done. For now I only took screenshots of the RP after you kill Balnazzar but I'll take some of the dead side as well afterwords.
Storyline: After the events in Northrend and Undercity, Balnazzar goes crazy and sheds his disguise. He kills the remaining Scarlet Crusaders and uses his necromantic powers to resurrect them. On live side story is pretty much the same except that Aurius has been resurrected to replace Baron Rivendare(It's not really explained in the quest text so this one is up in the air).
After you kill Balnazzar a bunch of Argent Dawn guards roam the halls and such. Overall I was impressed some actual depth and story is being added to these dungeons. I mean they already had it but not as much as now.
*Update*
Only boss that's changed was Rivendare unfortunately. Same deal afterwords. When you kill Aurius Rivendare Argent Dawn NPCs appear all over the city.