I tried with my friends, but it takes too much time, and it is very hard. We wanted to make 2 campaigns for the beginning:
Undead campaign (which is a very old idea)- Arthas sends Anub'arak to help Kel'Thuzad to siege Ironforge. First they deal with the Forsaken (Sylv flees with her minion), then they split beneath the forests of Khaz'Modan, doing separate missions, and they regroup beneath the walls of Ironforge. After killing Magni, Anub'arak returns to Northend.
Blood elf campaign- Illidan is death, now Kil'Jaeden wants Kael to summon him through the Sunwell promising big power to his race, Kael kills Kel'Thuzad, but when the summon ends Kil'Jaeden actually kills Kael. The BL enters Azeroth again, and in the last mission Vashj has to run through the forest filled with demons to rejoin the survived BE and flee to Kalimdor with them. This is the shortest as possible.