With the announcement of a new class to be introduced in The Elder Scrolls Online, change tokens are a hot topic in the community again.
The official answer:
Hi everyone, just wanted to let you all know that we do not have any plans on implementing class changes tokens at this time. There are a number of technical challenges with implementing them, and it would take a significant amount of time to solve these challenges efficiently and safely.ZOS_GinaBruno – forums.elderscrollsonline.com
New Class and Additional Character Slots
Whenever a new class is introduced, there is the problem of unavailable character slots. To address this issue, an additional character slot will be included in the purchase of the ESO: Necrom and another will be available for purchase in the crown store. The total number of character slots will to 20 slots. (Source)