I would really love to see this, but not ganking where you just stab somebody from the back when they are just minding their own business. I would like PVP to be Fantasy Earth Zero style, it was a square enix game, 50 vs. 50 in some location, maybe instanced. Nothing increases morale and linkshell pride more than winning a hard fought battle against another linkshell using teamwork and strategy. Some people aren't so willing to actually fight, but to make them participate, they can be tasked with building fortifications, summoning creatures, artillery, or maybe mining something. For example, have botanists and miners, which are nonbattle classes run to gather some ingredients to make that wall or building. A crafter only job can participate by manning the artilleries. DoW and DoM jobs can simply attack at anytime. Maybe limit the entire battle to about an hour, so it doesn't feel like it's too long. Rewards go to persons with most kills or most contributions, etc... But shouldn't be too great of a reward that people stop hunting NMs. Should be just another alternative to grinding to level up. Maybe have a ranking system based on performance. Also allow random players to join mid-battle whichever side has a lower number of players.

I would also like to be able to take over a piece of land, like in ffxi, but at the linkshell level instead of country.

Also, why limit it to just person vs. person battles. I would like some ship to ship or airship battles. It would be so exciting to have one person maneuvering, one barking orders, and a bunch on the guns, and several preparing to board the ship. This doesn't have to be linkshell vs. linkshell also, it can be a little mini game fighting the Garlean Empire. If it's linkshell vs. linkshell ship battle, should allow the leader to challenge the other ship to pvp, instead of just catching them off guard.