If they're going to go custom I'd love to see them create some completely new zones from the ground up (meaning not recycled zones from SoL/PoP/LDoN). There's so much creative potential there for designing new zones and items that would fit into both the lore and geography of classic EQ. I would also love to see additional quest lines and more rare, high-end crafting options. Some ideas off the top of my head:
- An undead dungeon in the Spectre tower in Oasis ("The Flooded Crypt"?) where parts of the dungeon are underwater and other parts dry.
- "Epic non-weapons": Epic-scale quest lines for each class that result in the reward of a powerful item, either a very useful clickie or an extremely good piece of slot gear. (ex: Monk item summons 250 range Javelins, Wizard item casts self-only Clarity, Cleric a ManaConversion shield, etc...)
- Extremely rare drops off common mobs (i.e. Sarnak Earring of Station) used in crafting recipes to make powerful new items/armors.
- A high level Orc dungeon in Highpass Hold.
- A Seb/HS style key quest dungeon for each other continent.
- A new Plane to explore: The Plane of Anti-Magic, where no magical items or weapons are able to be equipped, and all spells are 50% less effective.
- New race/class combos: shorty hybrids, Barbarian Paladins, Dwarf Shaman, Dark Elf and Wood Elf Monks (<--- that last one alone would have massive potential for some really cool custom lore and quest lines)
- Modified leveling system that requires the completion of a quest to progress every ten levels, starting at level 20. Example: in order to level past 20 (then 30, then 40, then 50) you would have to finish a decently-involved quest that would require you to visit many of those level-range specific zones/dungeons across Norrath. The idea here being to encourage (read: force) people to utilize more of the game's content rather than speed-level in the same handful of easy XP zones.