Hello. I realize that:
1) Theories about Sylvanas and future leadership and undead paladins have been done to death.
2) Undead feel pain when using the light.
3) Arthas was 1/2 of the lich king. Arthas' body was used, but ner'zul's mind and motives were controlling this body. If you don't remember, Ner'zul needed a person to act as his body as he was trapped in the Frozen Throne. So he sent the Dreadlord Mal'ganis to antagonize Arthas. Driven to protect his people, he chased Mal'ganis to Northrend. When he got there, he realized that He most likely could not defeat Mal'ganis. He needed an advantage to beat Mal'ganis and save his people, that advantage was Frostmourne. When he took the sword, his power became massive, but he started hearing whispers from Ner'zul. Much like how Yogg-Saron corrupted the Keepers of Ulduar, Ner'zul corrupted Arthas.
4)Arthas' burial ground has not been announced or mentioned.
Also, before I begin, I would like to state this is not a plea for undead paladins. It involves the undead being paladins to create a larger story.
Ok, We have all heard that Sylvanas has been raising new Forsaken using the Val'kyr so the Forsaken don't die out. So if Arthas was buried in Lorderon (Or any other place for that matter. Even if Arthas' body was left atop the frozen throne to rot, Sylvanas could go retrieve it.)Sylvanas could have one of her Val'kyr raise Arthas. Now realize, if Arthas were to be raised, he would be raise as Arthas the paladin, not Arthas after he became the Lich King. He would be still be driven to protect his people just as he was prior to taking Frostmourne. The twist at this point is that his people are now the Forsaken.
It is reasonable to beleive that a Paladin of immense power such as Arthas would retain his powers in death much like Sir Zeliek did. (Blizzard has already stated that a paladin does not need to be in an order or a member of a certain race to use the light, all that a paladin has to do is legitimately believe he is doing good.) If Arthas was raised to serve Sylvanas, he would notice that she is making similar mistakes as he made. Both went to extreme lengths to help there people. He would most likely speak out and try to warn Sylvanas.
Obviously, Sylvanas would completely disregard Arthas and continue to raise the dead. Arthas would at that point break away and form a group of Forsaken Paladins who would accept help from anyone who opposed Sylvanas, including the Alliance, and members of the Horde who don't think what Sylvanas is doing is right. The people who became Forsaken Paladins would be like Lilian Voss in that they do not accept Undeath and the way that the Undead are turning. Below is Jesse Cox doing the first part of the Lilian Voss quest chain.
Eventually, the group of Forsaken Paladins headed by Arthas would have received enough help from various sources that they feel they are able to take down Sylvanas. in a one time world event, Arthas will lead a siege on the Undercity. He will force Sylvanas along with the remaining Val'kyr and those who support her to flee the Undercity, and take up residence in Tirisfall Grove. Arthas will become the New leader of the Forsaken, Players can then create Forsaken Paladins, and Arthas pledges not to raise any new Forsaken in any way, shape, or form or use the plague.
Sylvanas can then become a raid boss in a raid in a later patch or even expansion. In Tirisfall Grove she would most likely create some form army with the few Val'kyr left under her control as she prepared to retake the Undercity.
Keep in mind, these events would take place over a long period of time.
Also, these events would cause something that really doesn't happen very much in WoW, advancement. Not only for the Forsaken, but also for the two races closely related to the Forsaken, being the Blood Elves and Worgen. They could both expand if the undead diminished (Especially Worgen because of not using the plague.)
The Forsaken would not die out because:
1) During the time Arthas was trying to build up his group of Forsaken Paladins, Sylvanas would have been raising new Forsaken continuously.
2) When Sylvanas is in Tirisfall Grove, as long as there are corpses, Sylvanas will have the Val'kyr raise them. Some of the raised corpses may not be to keen on trying to kill hundreds of innocents in the undercity and will try to escape.
Koitra and Thassarian's story could be involved in some dimension of the greater story, Koitra could be freed during the siege of the Undercity and Thassarian could be a member of Arthas' group. After the Siege, they would both return to their respective capital cities and sit there until they are needed in a story again.
I was brainstorming ideas for rewards and here is what I think could work: Title "
Name Bane of the Banshee Queen", Undead bat flying mount, Undead bat companion pet, moderate gear comparable to the level of gear available from the Argent Tournament purchasable with champions seals (ie
http://www.wowwiki.com/Sen'jin_Beakblade_Longrifle ) Or a skeletal warhorse using the same model as :
http://www.wowwiki.com/Ochre_Skeletal_Warhorse or a recolor of it.
Please post your ideas/critique and tell me if I overlooked anything. thanks for reading.