Something i wish they'd look into is adapting the HSR (Host State Rewind) that the team over on MechWarrior:Online built. Granted, thats an FPS game, but i feel like the general mechanic there, which literally eliminates Ping as long as its 400~ or lower, starts to get a lil shaky if you get too high over that, but generally works fine up to 500.

What it does is tracks/records the geo position of all players, and uses a sort of rewind server side to see if the target was where the bullet/laser passed through.
What it means for gameplay is that at a latency of 250, i can shoot a latency 10 player square in the face from 500 yards, and as long as my bullet hits the target on my screen, the damage will be applied to the guy i was shooting at, no matter where his client says he NOW is, so i don't have to guess how far ahead of the target i need to shoot to compensate for lag.

What it is, in its simplest form, is {Server Authoritative, Client Side Hit Detection}. Adapting this system to work here in an MMO would basically eliminate Latency as a gameplay factor for the vast majority of players.

For us here, i think it could work with modification.