France is doing everything in its power to keep companies from going there and employing people (by improving worker conditions to the detriment of employers).
But the French government budget would surely also benefit from a devaluation here and there as it always did.
On the positive side, without the EU the French agricultural sector would have to face the plain market and get along with a few dozens of billions less per year, so there's that.
For a little bit more data I cannot recommend enough the Economic Libery Index: http://www.heritage.org/index/ranking
France is 72nd, quite a few ranks after countries such as Albania, Kosovo, Rwanda, Kazakhstan, ...
Unsurprisingly, Government Spending and Labor Freedom are the worst elements of its index value.