This is just completely nonsensical.
You have no idea which country is going to be rich in the future; Sudan if it ever gets its act together could be extremely rich. Maybe it's better to treat everybody like human beings instead of consigning people to death who might someday be richer than you.
Nick Beckstead, noted longtermist and "effective altruist,” just comes out and says it:
"But it now seems more plausible to me that saving a life in a rich country is substantially more important than saving a life in a poor country, other things being equal."