Highly doubt the barb will replace the monk. Barb literally only brings 25% DR and 20% dmg debuff and some pulling(the DH can alrdy do it).
Monk brings 20% and 40% DR debuffs, 55% DR buff if standing in it, 30% dmg debuff, pulling, healing with soothing mist(this is highly valuable now that there is no globe healing and the group otherwise has 0 healing).
The DH brings more DR than the barb and way more dmg buffs as well and WD has no reason to be dropped.