Given that Sylvanas is such a significant part of WoW from wangyue's blog

The Maw Primarily serves as World of Warcraft WOTLK Classic' Endgame content, and it's natural to WOW WOTLK Classic Gold  assume that the WoW's Arthas Menethil will be in the Maw. 

A majority of the content will have a connection to Sylvanas in that she was killed by Arthas during Warcraft 3 before Arthas resurrected her. 

Given that Sylvanas is such a significant part of WoW: World of Warcraft WOTLK Classic With such an extensive relationship with Arthas and Arthas, it only makes sense he'll show up in some way.

As we approach the beginning of the content that will be ending in World of Warcraft WOTLK Classic, Sylvanas discloses her plans to alter how the afterlife operates.

 While her reasoning isn't completely clarified (Sylvanas remains Sylvanas in the end, after all) however, it definitely opens the way for players and Sylvanas to meet World of Warcraft's Arthas Menethil once more buy WOTLK Gold. It's likely that Arthas will make an appearance at some time when it comes to World of Warcraft WOTLK Classic, even if in the future after the launch.