I think you are wanting more thinking time for this , Ok.
Tell me tomorrow whether there is any way for organised labor to remain relivant with a planetwide availibility of scab.
Planetwide availability of scab? Now you're just being silly.
I'm not sure if you're making a case against immigration or against international trade.
Okay, that was laying the sarcasm on a bit thick. I admit that. Even so, this infinite/inexhaustible supply of labor objection you keep trying to press seems a bit ridiculous. If all labor in all fields of endeavor was exactly the same and all access to it was exactly the same, you might have a point. But it isn't and you don't.
The qualified persons are of course a subset of all humanity and not absolutely infinate, but unions bargan by threat of boycot or strike. Infinity is not needed , just the manpower required to operate without the union.
Are Unions going to be relivant in an environment of plentifull labor?
I think this is a relivant question because we are already in times of declineing Union influence. Where immagration sometimes overwhelms local labor , the job can also migrate with the manufacture or service being performed in a new venue near the cheaper labor.
Perhaps the truth is that Labor Unions need to be absolutely international to be effective , perhaps the answer is that we will have to do without Unions as they slowly fade from modern life and join the livery stable as quaint , rare and irrelivant relics of the past.
Neither of these are acceptable to Unions , they still advocate buying American production and hireing citizens , even closing shops , as if the industry were impossible to move or to staff without the union.
So do you think that UNions must adapt or die?
I really think so.