Thief and Ranger definitely deserved to be their own jobs instead of being fused into Ninja and Bard respectively. even though the game has shifted away from debuffs and aggro management, I still feel like there's a lot you can do with Thief if it were given the chance to be real.

as for if Viper will bear any resemblance to Thief/Rogue/Assassin/whatever, we'll see in due time when we get more information on it next year and I kind of hope it does. I would be incredibly disappointed if Viper's only identity is that it has a hybrid weapon and that's it.