If a hub is entirely focused on a single product and you are getting decent traffic for it then keep it! Just remove the expired affiliate link and treat the hub as a review page. Change your title to make it clear that it is a review. There are 100s of pages on the web that still mention expired products.
If you feel uncomfortable with promoting a product that won't earn you any revenue then go ahead and unpublish or remove your hub. If there's no traffic then you might as well remove it.