Authenticators to be required to play WoW?

[Sheep]

Will there be legal implications in all of different countries if Blizz forces you to pay extra (even once) to be able to play a product you already paid for? (anwser: yes).

They're covered in the terms of service, item 7:

NOTWITHSTANDING ANYTHING TO THE CONTRARY HEREIN, YOU ACKNOWLEDGE AND AGREE THAT YOU SHALL HAVE NO OWNERSHIP OR OTHER PROPERTY INTEREST IN THE ACCOUNT, AND YOU FURTHER ACKNOWLEDGE AND AGREE THAT ALL RIGHTS IN AND TO THE ACCOUNT ARE AND SHALL FOREVER BE OWNED BY AND INURE TO THE BENEFIT OF BLIZZARD

Furthermore, even if that doesn't quite cover it:

Blizzard reserves the right, at its sole and absolute discretion, to change, modify, add to, supplement or delete any of the terms and conditions of this Agreement at any time, including without limitation access policies, the availability of any feature of the Game or the Service, hours of availability, content, data, software or equipment needed to access the Game or the Service, effective with or without prior notice; provided, however, that material changes (as determined in Blizzard’s sole and absolute discretion) will be disclosed as follows: Blizzard will provide you with notification of any such changes through a patch process, or by email, postal mail, website posting, pop-up screen, or in-game notice. If any future changes to this Agreement are unacceptable to you or cause you to no longer be in compliance with this Agreement, you must terminate, and immediately stop using, the Game and the Account. Your continued use of the Game following any revision to this Agreement constitutes your complete and irrevocable acceptance of any and all such changes. Blizzard may change, modify, suspend, or discontinue any aspect of the Game at any time. Blizzard may also impose limits on certain features or restrict your access to parts or all of the Game without notice or liability.

End result being, there will be no legal ramifications, just disgruntled players.