Will the changes seen to the world as the streets get cleaned up be like the phasing in WoW's Wrath, or will they be global?

If a player makes a new character a year after launch, after everybody who started on day one has cleared that lowbie zone... will it be so clean there won't be anything left...

Or will it be an all over again thing for each character, via phasing, so that the game can keep being fresh over and over again for new players as well as for new alts.