Production is expanding elsewhere in SE Asia but those countries are much smaller and taking time and a lot of capital to ramp up.
Where are all these new workers going to come from, and if they could work productively already why aren’t they?
None of this makes a lick of sense.
Why would they work more productively if that is not needed? They would have to make more things, which people wouldn't buy because there is overproduction. If you have order for 1000 items every week, you make 1000 items every week, even when you could make 5000 items every week. You can slow your production line, this way workers are more relaxed and you have time for maintenance. It's not like every employee out there is used at 100% utilisation, that would not be sustainable. Many times you employ as many people as you can just because it's cheaper than using more automation. If you need to produce more and can't find employes, you can pay them more. If you can't find enough employes at all, that means price per employee is so high that you can now employ some robots. Yeah, it takes time, but global change in time of employment is also not going to happen overnight.
So, we provided more products to people who now have money. And now you are asking "Who will pay". Well, the people who now have the money to pay for it? That was the reason for increased production in the first place?