There were many in the Soviet Politburo who thought that going into Afghanistan was a bad idea. Say they manage to convince Brezhnev that it is. What would happen next? I can see the situation in Afghanistan leading to a civil war, with the USSR giving the communists military and monetary aid, while the US, UK and numerous Muslim majority nations do the same to the Mujahideen. A surviving Taraki (which would most likely be the POD for this) leads to the PDPA becoming more unpopular than IOTL which, along with less Soviet involvement leads to an earlier victory for the Mujahideen possibly around the mid to late 1980s.