It may appear to be a difficult question as you wrestle with it, but it's actually a boon to your application efforts. So many other folks don't know what they want to do, they end up looking very unfocused and unprepared. You will do well in your applications not only because you know your intellectual interests and have a depth of knowledge already, but also because you will hone in on the particular schools and professors with qualifications that YOU will set out as important.

My only caution is that there may be schools that don't have a particular degree in French Linguistics but do have an excellent professor or two in the area. Those schools might be very appropriate options for you as well.

Best of luck!