There is room for decent optional horizontal upgrades. The CoP ring was a good example of horizontal done right because the ring scaled vertically as you gained higher levels. Gear made in this nature also helps item bloat lower tremendously. For a horizontal method to work in 14 it would have to do three things.
1.Stat attributes would scale by level Lvl30=Str+X,Lvl40=Str+X,Lvl50=Str+X,Lvl60=Str+X.
2.Ilvl upgrades would be unlocked by special spiritbonding in specific ilvl content. To upgrade ringX=Spiritbond in dungeonX/specific ilvl combat.
3.More content to flesh out pacing at lvl 50,60,70,etc.

This would also give people another reason to want to run older content for more than xp/achievements or tomes helping newer people advance through the dungeon treadmill. They would want to upgrade their items before proceeding to the next wave of ilvls.