I posted that idea more than a year ago. Almost 100% of the posters thought that was a horrible idea. They didn't want DDP diners to be treated as "second class" customers and not be allowed to order the "good stuff".
There is a restaurant near where I live that offers a Friday night priced fixed dinner special. All the promotional materials say Any Entrée, Any Appetizer and specifies a special dessert. At least half the items on the menu have an * with an upcharge. I stopped going there.
Having upcharges is a slippery slope. It might be reasonable to offer one signature dish, such as lobster but that probably won't be enough to satisfy the "foodies". Having an upcharge for more than one or two items and the DDP guests will have a right to be upset.
My guess is Disney would exclude a second restaurant (from the dining plan), if they thought there were enough customers. A signature restaurant is credited $50-55 per guest. That should be enough money to provide a reasonable menu. I doubt there are enough guests willing to pay $76-$100 to justify having a restaurant positioned above the current signature restaurants but below V&A.