It will remain to be seen. There have been plenty of stallions who have made an impact with their first crop, only to fade into oblivion - DAGGERS DRAWN, FASLIYEV, etc.
Next year will be a crunch year for him. His offspring will need to prove they can train on.
Galileo is certainly making an impact as a sire of sires, his 4 sons at stud with runners (Teofilo, Heliostatic, New Approach and Sixties Icon) have all managed to sire Group horses. However you could argue that Sixties Icon has been equally, if not more, impressive than New Approach.
From 17 runners he has had 8 winners (47%) and 6 placed horses (New Approach has 9 winners (26%) and 11 placed horses from 34 runners). Bear in mind that he has had limited opportunities (52 mares covered compared to New Approach's 136) and the mares sent to him to date will have not been of the best quality.