I suspect the progression would be ATR, SO on 777, then right hand seat on the 737 in NZ or Australia.
I keep hearing that, but why do you assume that? Surely new hires regardless of their initial type in company have a seniority number these days and can bid for fleet and base transfer as they wish? Sure they might allow only 10% off the ATR fleet in a year (although I thought that was VARA... despite still having an EBA with VARA isn't the ATR operation part of VAA now?) but if an ATR pilot has a higher seniority than a 777 SO then surely the ATR pilot will get the 737 position first if both have bid for it and there is no one with higher seniority to take it first?