Most I know who emigrated from Iran in the 70s did not return later on and never planned to; however the actual reason for that was that those were teenagers in the 70s who were pretty much dodging the draft under the Shah, and were definitely so not going back in the 80s while the war with Iraq was going on. Not when there were another 15,000 Iranian teens being smuggled out of the country and into Germany for the sole reason of avoiding to have to serve in that war - and those 15,000 kids represented about one third of all Iranians fleeing Iran for Germany during that time. Rather notably the overall immigration numbers of Iranians dropped off extremely after the war ended (and, frankly, after the regime had already cracked down on Shah supporters in Iran in the mid-80s).