Average wage in Dongguan is about a quarter of a Dublin wage, according to this.
Probably closer to a fifth or a sixth when factoring in the weekly hours, as you pointed out.
Still a huge huge saving if a project is likely to involve hundreds or thousands of man-hours labour.
Plus the plant and the experienced technicians are already in place, avoiding start-up costs and quality issues due to inexperience.
It would take a very bold investor with a lot of patience to start manufacturing in Ireland, and a market willing to pay ten times the price per item.
Maybe with time, as Ireland becomes reknowned as a manufacturing capital, more companies contract Irish manufacturers, and economies of scale kick in, prices would drop.
Possible, definitely possible, but probably not probable.