KMS and 4th tier potential.

There is a slight possibility that 4th tier items might revert to 3rd tier, because 4th tier on level 130+ on every piece of equipment is totally worth adding 2ndary stats to equip. Nexon might deem 4th tier too powerful when we get a level 130+ item for almost all types of equips. With the release of higher level hats, overalls, belts, gloves, shoes, etc, players can theoretically gain 5% more on each piece of gear. On the other hand, you can argue that existing 4th tier items may stay because: 1) we don't know if the item's potential can be changed with a server check or 2) Nexon might not revert 4th tier stats because that'll be a plantain move to NX users with VIP items. Either way, Nexon has repeatedly shown in the past that they don't care, as with Elemental weapons.

Those are just my predictions for the future of 121+ potential items.