This is looking more and more like Afghanstan Part 2. Fanatical Islamist rebels retreat from the cities and hide in the desert/countryside to avoid open combat.
Well, to be fair, unlike in Afghanistan, only the north of Mali is so mountainous to offer a potential refuge for Islamist fighters. Also Malis direct neighbours aren´t really interested in the creation of a safe haven for extremists as the Sahel zone can´t really be compared to the Tribal Areas of Afghanistan and Pakistan.
Additionally NATO/the EU aren´t running the show alone. Neighbouring ECOWAS states are bolstering their forces and support for Mali, as well and as soon as the islamists are driven from the cities the goal is to let this become an "African affair". The French only acted because noone else was willing to protect the Malinese government and I´m quite sure that they have the least interest of becoming bogged down in an "eternal" conflict.