I have a similar question, but related to Motivosity, which we use for peer-to-peer bonuses, with an associated rewards store.
Motivosity has an open API, so we're evaluating the option to integrate Jive with Motivosity.
I can confirm that this isn't on the roadmap (probably ever), after talking to their Director of Product Management at JiveWorld, since I had the same question....so we'll be keeping Bunchball for now since it meets our needs there. They mentioned it won't be in the cards, since most of their customers don't require it.
As Ryan mentioned, that is correct. Rewards store is currently not on our map.
We do have a plan on our roadmap (No timeline yet), to provide Rewards public API. That will enable you to integrate Jive Rewards with external systems. Store can be one of them.