I could see playing around with him a bit, but I'd suggest not royally screwing him over. He blew a feat on it. Why does he deserve to be punished for one of his feat choices? If you don't like Item Familiars, then don't allow them in the game.
this cannot be emphasized enough.
Don't get me wrong, this is not what I'm after. The campaign starts with this PC in prison, so naturally his ring has been stripped of him for a long time. Rather than the penalties resulting from this being permanent, I house-ruled that they are temporary until he gets his ring back. He only felt withdraw symptoms within the first week of being separated from the item. So a fetch quest begins here (and I'd like for it to be the only one, since they are tedious and offer nothing to a campaign).
However, after the fetch quest is done, what kind of stuff can I do to make the item a bit more significant? I was thinking, on occasion, using the spell
Grim Revenge (BoVD), which basically rips his arm off and have the arm beat his silly. If the arm that contains the ring is removed, so is the ring's powers.
... The best thing right now is to embellish the chase as much as possible. Have near-grabs where the ring rolls away, falls into a cavern for a dungeon adventure. Inside they will fight a level-appropriate dragon, which probably means a wyrmling of some sort...
Basically, don't just make this a little, forgettable task. You have a plot on your hands.
This is a neat idea and it has inspired me to make into a chase. Your idea of using goblins and wyrmling fits well into what I have planned for the campaign. The drawback is that I cannot keep it away from him for too long. He is rather gimped without it, having invested spell slots and skills in it.
Because of the ego contest that ensues when an item like this is given to a new owner, I was thinking it might have a Lord-of-the-rings-esque twist on it. A Goblin comes to own it, the ego contest ensues and the item begins to taunt him and mold his inferior will. This 'Goblin Frodo' will then be convinced by a friend that it's imperative that it be destroyed, it's cursed they say! So they venture to some underground setting and try to destroy the item in a poor-man's-mount-doom type lava pool. This works well in Sharn.
This may not be as epic as the LotR books, but there is some detective work that needs to be done. Since the party is generally unscrupulous, houses may be broken into and knees might be bludgeoned to get some info.
I wonder how this would look to the characters, not the players. Like the ring being too powerful for the goblin to even hold...
Plus the player might boast "I can kill goblins with my ring" which is all sorts of wrong
"My precious?"