After spending hundreds of hours playing my alliance players on WOW TBC Classic Gold a pvp server this really feels like a huge disgrace to me through the blizzard. This will give the dominance of hordes on all pvp realms. Alliance will not be possible in open world. It is evident by the classicwow subreddit's reaction. Wow is a lost cause and the playerbase is complete rubbish.
Developers and players convert the traditional into retail, gg.

Do not do it. you think that you'll keep playing the character you have in Classic but you'll never, especially if you have already cleared Naxxramas. If you want to continue playing Vanilla, just start over with a brand new character. It's going to be much more fun and fulfilling

Individuals who wish to reach max but do not have the funds to achieve it yet, can do it with the tbc changes or remain in the classic. They could join new guilds, and then begin to raid nax entirely from scratch with a new raid. If they wish to play tbc then they'll have to pay an cloning service in order to get to tbc, or begin by scratch. Since the original wow community is no longer around, the cloning service ought to be free.

All current servers will become TBC servers. Open the new Vanilla versions of these servers. There is the option of activating the character in either the Vanilla or TBC version. You will need to pay to cheap WOW Classic TBC Gold activate the same character on both.