In game? I’m literally in a group doing a quest right now. Tons of people are leveling.
Also, if you mean paying extra… Every character gets to be activated for free the first time. Its only the second time you have to pay for.
For instance:
My rogue will be on BOTH TBC and Classic Era servers on May 18th. I get to pick which one I want to play on for FREE. If I choose TBC for my rogue its free and my classic rogue will go inactive. If I want to play on Classic then I have to pay 35$. I really don’t know how to be more clear about it. Just go read the support article.