My mum used to say it was like losing a leg. Her eldest child moved there in 1968 at the age of 20, newly married and with hopes for the future. A few years later, my brother joined her. It was a traumatic time for the family.
There was no inter-net, no cheap flights (people still went by boat), we didn't even have a telephone.
We did record tapes on a neighbour's machine, we sent regular air letters, photos, and there was even the occasional parcel.
When they came back the first grandchild pregnancy was announced, and they went back to Australia when he was about two years old.
My parents went out to see them all (more GCs had arrived) about ten years later- the first of many trips back and forth.
It has marked our entire family life, but I have visited four times and my sister is now 80 years old.
We are all in constant touch with the whole family and still get frequent visits from nephews, neices and their significant others. This Christmas my great-niece will be visiting with her new partner.
It is possible to keep those ties very strong, maybe even stronger, over such great distances.
It becomes a way of life and I hope it will become so for you but it takes work, and obviously money as the days of really cheap long haul flights has now gone.
Your GC will have a great life there, but there are difficulties too as everywhere.
My nephew also emigrated but came back twice.
The situation is far more fluid than you might think and maybe you'll go there and maybe they'll come back but just steer yourself for lots of wonderful adventures along the way.