It’ll come down to moneyAustralia and NZ are the best places for school/employment etc in the Pacific, As such they will always get Samoans/Tongans heritage players.
I found them to like both sports, So in theory getting the switch is possible. Reality probably not NZRL needs to get itself in order 1st
nrl salary cap will keep going up to a level they can’t compete with
the days of an nrl player getting a base salary of 2 million pa aren’t far off
though I doubt any club would actually be dumb enough to pay an all black that much