White grapes: Adding white grapes would give you something new to do with your vineyard, which would be a fun addition to something that currently only has one use/produces one item. They could be unlocked via a high-level Farming quest (maybe level 99?), perhaps given by Cecil or Jill, since they're our canon grape-enjoyers. White grapes could be crafted into sparkling wine.
Sparkling wine: (So, champagne, but calling it such to avoid the "it can only be called champagne if--" thing.) Sparkling wine could be aged in the cellar, which could give later-game players something to do with it, after regular aged wine has become less relevant. But it could also be crafted into...
Mimosas: Oranges/orange juice kind of stick out from our other orchard fruit and their beverages, which already have items that expand or boost their usage (Arnold Palmers, lemon cream pie, cabbage stew...). Mimosas could fill that niche. I don't have a firm idea of what benefit mimosas could give, but perhaps they could be used to give a small boost to the next day's orchard production, since later/end-game players will eventually hit a hard wall where they can't continue to upgrade their orchard?
