Wharf doesn't resolve until I've gotten my +2 Cards/+1 Buy on my next turn.
This is wrong. Wharf is completely resolved right after you play it. The thing it does when it resolves is to give you 2 cards and a buy now, and to give you 2 cards and a buy at the start of your next turn. It's not still being resolved on your next turn.
Hmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm.
Think of it like this: the game has these event-triggered "thingies" that say "When X happens, do Y."
Sometimes, one of those thingies lives on a card and it's always there. Like with Border Village. "When you gain this, gain something cheaper." That's easy.
But, sometimes, something
creates one of those thingies out of thin air, and, since the thingy doesn't live on a card, it kinda floats around waiting to be triggered. That's what Wharf does. When you play it, it gives you +2 Cards and +1 Buy, then it
creates a floating thingy that says, "At the start of your next turn, +2 Cards and +1 Buy." Then Wharf is done; it's resolved (and you can Coin of the Realm it), but the thingy it made is still floating around. Later, an event (the start of your next turn) makes that floating thingy trigger (giving you +2 Cards and +1 Buy). And, since that event can only happen once (you only have one "next" turn), the thingy can't trigger anymore, so it's effectively gone.
(That's why duration cards usually stay out, by the way: as a courtesy to remind you that they made an invisible floating thingy that's still hanging around waiting to be taken care of.)
Prince also makes one of those floating thingies. But, unlike Wharf's thingy, Prince's thingy triggers on an event that can recur (the start of each of your turns), so it sticks around (potentially) forever. But, similar to the Wharf case, Prince was finished resolving after he initially created the perpetual thingy, so you can Coin of the Realm him, too.