there's some work that needs to be done to make them all 1 item, that will be coming out after the initial release :)
so, maybe never, but good news if it does happen! wonder if the extra damage will cost 5x cannonballs or something
no, not never! I will make sure it happens, just can't give a date right now :)
(and no, the extra damage will not be 5x cannonballs, it will require an upgrade item for each cannon type)