Unfortunately the Assad Regime and the Russians who are actively assisting them are making the efforts of any Western allies to do so very difficult. It is not only that but the fact that ISIS is also still present in various parts of Syria making any organized evacuation difficult. Not to mention the fact that ISIS might send fighters through posing as refugees, which has already happened.
But that aside, Aleppo is currently free and ISIS has been sent fleeing from the city with their tails between their legs.
The main problem however, as mentioned, is the existence of a Russian backed Assad. Attempting any moves on their controlled territory is likely to lead to a diplomatic incident.