I think there’s no stopping this train. Whoever doesn’t train on all available data will simply not produce the models that people actually use, because there will be people out there who do train models on all available data. And as I said in another comment, after some number of decades all of the content that has been used to train current models will be in the public domain anyway. So it will only be a few generations before this whole discussion is moot and the models are out there that can do everything today’s models can, unencumbered by any copyright issues. Digital content creation has been made mostly obsolete by generative AI, except for where consumers actively seek out human-made content because that’s their taste, or if there’s something humans can produce that models cannot. It’s just a matter of time before this all unfolds. So yes, anyone publishing digital media on the internet is contributing to the eventual collapse of people earning money to produce content that models can produce. It’s done. Even if copyright delays it by some decades, eventually all of today’s medial will be public domain and THEN it will be done. There are 0 odds of any other outcome.

To your last point, I think the best case scenario is open source/weight models win so nobody owns them.