I've noticed a couple of things since I returned to Paris after the Charlie Hebdo attack. First, The military patrols now consist of a full squad of 7 soldiers instead of the usual fire team of 3. They are organized in the familiar squad column formation with full 360 degree security. And all are carrying the FAMAS assault rifle.
Second, I see almost no muslims on the trains or the streets. Before the attack, women in head scarves were prevalent. Muslims could often be seen reading the Koran during their train commute. Now they are nowhere to be seen. Train ridership seems to be lighter. I'm not sure if that is because of the lack of muslims riders or of a public fear of an attack on the train system. I subscribe to an automatic alert about problems on the Metro and there has been an increase of the number of service interruptions due to "suspect packages".