an idea..

upgradeable legendary items via quests
for example say you get the mine at level 700
at level 725 you can do a quest to recruit miners FOR the mine and when u complete it it increases the income of the mine
at 750 you expand it, and at 775 you explore a chamber that opened up in the mine that perhaps gives you another legendary or something
just a thought ^^

Thats an excellent idea! I can imagine a drop down menu on some of the quests, as a 'questline' you can do as you go. That'd be an awesome thing...

great idea