Thanks for your good reply
I agree there are still relatively empty spaces in the world. But there are also reasons for that : deserts, mountains or other less favourable locations. But space is not the only thing : we need to feed all those people and I'm not sure if that is sustainable. But I agree it's not a critical issue right now
Agreed also on the immoral part. The welfare state I'm not so sure. Some people will still just have the children and don't think about consequences. They know we will not let them die...
Indeed of there are too many grey people supported by new blood there is indeed another issue. Maybe we should reform social security into a individual supporting system to mitigate.