I saw in an EU Fan Fest interview the following:
If this refers to an instant "0-50" (or even worse a "0-60") jump, don't do this. Please.JP Outlet: There’s been talk about introducing a quick leveling potion (jumping potion) and i’d like more details about that.
Yoshida: This is something we’re still debating in the team. We can’t say anything now but we hope to have an announcement soon during a live letter.
Level skipping does not force people to learn their classes, and then dilutes the pool of experienced players in endgame and near-endgame content. People need to learn their rotations and how to play in easier content.
Instead, continue to provide incentive for high-level players to run older content. Wonderous Tails, Roulettes, item and supply drops from older dungeons and raids all are perfectly fine.
In addition, you could provide gear that gives a generous XP boost under level 50 or so.
FWIW If I got this news all wrong, please say so.