Dual Spec NPC INGAME?

Would it be possible to Implement a Customize Dual Spec NPC in the game so we can Change spec without having to log off?

Like putting a NPC in Shattrath Where you can go and Change spec INGAME?

All while having to pay 100G(First time) too this NPC?

It would be easy to do, i think People would like that Feature so much, Not having to log off everytime.

Very much possible, but we don't want to implement custom NPCs.