Ratatouille had such a "happily ever after" ending with running the restaurant. And Remy doesn't have long to live anyway.

What are they going to do with a Ratatouille 2? Have a health inspector come in and shut down the restaurant because he finds rats and feces? Maybe Linguine runs a food truck?

Colette and Linguine aren't even all that appealing as characters. And I don't even want to see them again. I don't even want to see a story where they get married.