It's still there "technically", just works even better. Simply switch from default IOR mode to DisneySpecular and that is effectively the reflective slot. But in non-metal mode, the 1.0 value maps to something like IOR 2 so make sure to clamp the texture with output (either directly in bitmap or with Output Node, etc... anything works) to 0.5 if you want 1.52 IOR material.
Mapping reflection is still necessary even for PBR, 100perc. physical correct materials would require microscopic displacement so yup, use that slot.
thanks man for the reply, i understand and tested it. But why do you need to overcomplicate things every time? just leave the ior and the reflection slot, there is no need at all to delete it. just leave it and give freedom to the user to do whatever he wants with his materials. Physical material without reflection is not a physical material in my opinion and noway i need to guess and clamp with disney specular... hope you understand