yes implementing this and something around the lines of, Guild upgrades examples of ideas:
Spending guild crowns for certain efficiency upgrades: All guild members increase attk dmg, crush dmg, slash dmg, more health etc etc
small bonus world map speed upgrade for all members
faster resource gathering for all resources or separate ones gold stone etc
ability to open a alliance bank for depositories of resources that can be allocated from your dedicated treasurer. The more crowns invested into this bank the more capacity this bank would hold.