This is what, in a way, happens at
Disneyland Resort Paris. They don't have the DDP as it exists in WDW, but you can prepay vouchers for your meals at the TS restaurants (excl. breakfast). Depending on the kind of vouchers you bought (menu gourmet, menu discovery, ...) you have a list of restaurants to choose from. In those restaurants, you have a fixed-but-you-can-still-choose-menu. You can for example choose between 4 appetizers, 3 entrees and 4 desserts. The price of your voucher is lower than if you had to pay for each plate separately. Next to that, the restaurants still have other options available for those that do not have the vouchers/ do not wish to eat the set menu.
ETA: now I'm going to continue reading on page 3