Yes, there's a new Hearthstone Adventure on its way, and we all wish Exodar was a disco, it looks like Karazhan is getting the funky makeover for this adventure. Seriously, watch the trailer. Hearthstone's trailers have been amazing, and this one is just so delightfully silly (disco makes anything sillier) that I challenge you not to watch it with a massive grin on your face.
Karazhan remains one of WoW's two most popular raids ever (expect an Ulduar-themed adventure or at least a titan-themed expansion in Hearthstone's future) largely for its amazing atmosphere (not to mention the fact that it was the first really "accessible" raid in the game.)
So far we've seen the first boss fight, the Silverware Golem, who summons plates as its hero power and then summons other silverware to buff said plates.
Karazhan is a location that we're going to be at least briefly revisiting in WoW (there's a pre-expansion quest coming any day now and some of the artifact acquisition quests involve going there) and is of course a pretty important spot to the history of the game's world. So seeing Medivh cut loose and throw a crazy disco party there is a pretty great subversion of the location's importance.
Hearthstone of course tends to take a sillier look at the Warcraft setting that WoW does (not that WoW isn't silly) and so I am fully behind this discofication of the Guardian's Tower.