First flights will arrive at the end of June, probably from Scandinavia (Stockholm/Oslo).
This article (in French) also says Oslo and Stockholm:
Exclusivité /Ryanair arrive à Vatry | L'Union
Can see some potential for this airport, especially for routes to Spain, UK and Italy. Eastern France is so underserved.
It's also 120km from Disneyland Paris, but unfortunately it's not motorway the whole way, don't know if to plan to change that...