At the very moment Blizzard releases Classic TBC, Blizzard themselves can create a one time copy of all existing Classic Vanilla characters and “paste” them to the TBC servers. …But wait there’s more!
Why is this good? People who never want Classic Vanilla to change will always have their characters, in an unchanged 1.12 state, to come back to. People who want to progress their characters through Classic TBC can continue seamlessly into 2.0, with everything they collected and achieved on the Classic Vanilla servers.
The catch: After this point, if new people create new characters on the Classic Vanilla servers, they cannot transfer or copy these characters to the Classic TBC servers. Players who wish to play Classic TBC after its launch, and didn’t already have a character on Classic Vanilla, will have to create a character and level from scratch. However, TBC did make the 1 through 60 leveling experience MUCH QUICKER!
This little compromise is done for two reasons:
1.) So the economies of future classic expansion servers don’t get diluted with “would be” unobtainable items, excess gold from multiple character copies or oversaturation of old materials from the last classic expansion servers.
2.) So people don’t feel “forced” to meet some sort of Status Quo by having special items from Vanilla servers before they transfer, to feel like their TBC experience is meaningful, long after the fact.
Don’t get me wrong: If you didn’t get to play the 2nd release of Vanilla (Classic), while it was “current”, the door to Classic Vanilla is always open to allow you to experience it! However, having rare or hard to obtain items from Classic Vanilla, as a player in Classic TBC, should remain as a symbol of said player’s hard work and dedication in Classic Vanilla, NOT a consolation prize that people can get years later and bring to new classic expansions and pretend to be an OG Classic Vanilla player from August 27th, 2019.