They can start selling new servers only in data centers outside France, move the current VPSes and eventually shut down or sell the data center. The transition can last years but it can be done.

By the way, my bet is that France lawmakers don't even know that OVH exists (unless they do some lobbying) and don't know it's the third largest in the world. Now that they know they'll be counting votes gained against votes lost for every option (and money too). Then they'll decide what to do.