This means that tens of thousands of AFTRA-SAG jobs may be eliminated in the long run.
Maybe. They're going to be eliminated for many reasons, including any new deal will cost more, so they will just hire fewer writers. Or use writer/producers who're paid differently. But every time I think the union is dead, and new technology or owners will sidestep them, someone shows up and sells employees on the virtues of union membership. So just because Netflix or someone is currently working outside the union system doesn't mean it will always be that way. Take a look at Amazon. They have all the money in the world. Now their workers are unionizing.
What concerns or interests me is that the networks are married to Hollywood and the AFTRA-SAG structure.
That's because they ARE the studios. Disney & ABC. Universal & NBC. Paramount & CBS. You'd be surprised how many independents are unionized, and how membership isn't restricted to work done in Hollywood. The studios long ago tried moving out of town thinking they'd escape the unions, and they followed them.