While I am not sure if I want Lost World to return, I think its potency is being exaggerated:
Even if they do reprint Lost World I feel like it wont be reprinted as is due to the nature of the card. I mean just look at lysandre and Lugia GX; get the 6 pokemon in the lost zone and just win like that? Either way I gotta give the prayers to ZoroEggs in expanded then.
Lysandre [Prism Star] is requires your opponent has Pokémon in the discard pile for you to remove them from play, and only removes one per [R] Pokémon you have in play.
Lugia-GX has to use its GX-attack, a once-per-game attack that costs three Energy and - from the translations I've scene - only works on your opponent's Active.
Put it all together and this is
not a reliable First Turn Win. Actually, as you can't attack T1, you don't even need to factor in Lugia-GX.
Without using your Supporter for the turn - you need it for Lysandre [Prism Star] - you have to fill your field with [R] Type Pokémon and force your opponent to discard at least six Pokémon,
and you need to get this hypothetical Lost World reprint from your deck to your hand and then play it as your Stadium for the turn. So no using Shaymin-EX (ROS) to help draw, or Tapu Lele-GX to search out Lysandre [Prism Star]. I'm not sure if it is even
possible to force your opponent to discard six cards (let alone six Pokémon) on the first turn of the game.
So what about when Lugia-GX can attack? On its own, you'd have to hit something like a Luxray BREAK with an Electrode (EVO) attached to it via Electrode's Ability
and a Klefki (STS) attached as a Tool to meet the requirements of Lost Zone. That's six Pokémon at once; you can play around with it a little, like having a Stage 1 with four Electrode (EVO) attached, but you get the idea. Most of the time, you'll need
another method of sending Pokémon to the Lost Zone or some "help" from an opponent e.g. your opponent using a card that sends his or her own Pokémon to the Lost Zone.
I could
see a Lost Zone deck built around Lugia-GX and [R] Types emerging, but the time and effort it will require to earn the win is merely a "fast" deck, not a broken one. It should take two or three of your own turns before you're setup to use both tricks available.
If they did re-release Lost Zone
and the original would somehow be too powerful... make it Lost Zone [Prism Star].