The main problem with this subject is that the abaya is not a religious clothing strictly speaking. It is not enforced by any muslim sacred text, a lot of muslim women do not wear it, whereas non-muslim women wear it. It is rather typical from the arabic culture than from the muslim religion (it originated from bedouin culture in the first place).
Here in France people are mad about secularism because of an old hate of Christian Church, but nowadays it is rather used to discriminate jews and muslims. (At school, yarmulke and headscarf are banned, but christian crosses are allowed if they’re not too big. Every day i saw people in school with christian crosses around the neck or as earrings, and no one bothered them, while they were harassing girls with a headscarf.)
Imo here the government is just creating a new debate on a stupid question, just to scare people about muslims and give hard right politicians a bone to chew, as they always do. While everyone talks and is afraid about what teenagers could wear, people talk less about the other laws they are passing, for having more control over Internet or whatever they want.