I think this sort of addition to the game right now is a must. At higher levels, when the leaderboards are for the most part solidified, the worlds become semi stale. Nothing is happening that is meaningful to the game world.
Incorporating this idea into game play would open the door to a number of avenues that could essentially better facilitate the games immersion value.
It wouldn't require substantial coding to achieve it, not in the likes of Forts per se where they were building something from scratch.
Using PQ's in this manner, the game could bring on titles to reflect a players "involvement" with the world, and have varying titles to correspond to that PQ. For example, doing a PQ that would lend itself to acts of law enforcement type, a player could progress in titles (i.e. Deputy, Deputy Sheriff, Sheriff, Deputy Marshall etc).
Doing one in the outlaw line could earn titles that reflect that line progressively.
You could incorporate a number of different things to reflect different play styles and game personas.
To further that, and add more diversity, and reasons to come back and "continue clicking" is that achieving variable degrees in such lines could offer exclusive items that give benefits. Some items, some sets.
Now, instead of having a dueler, you can have that stage coach robber by title, earn gear that is tailored to it, and achieve it through the means of PQs.
This is the formula most all MMO's have adapted. This game needs one thing for sure, and that is better immersive qualities for late level gameplay. I see this as a definite path that could open a lot of doorways to keep people with the game.