Will they be willing to offer their content for training AI models?

Probably not.

We have witnessed, over the past few years, an "AI fair use" Pearl Harbor sneak attack on intellectual property.

The lesson has been learned:

In effect, intellectual property used to train LLMs becomes anonymous common property. My code becomes your code with no acknowledgement of authorship or lineage, with no attribution or citation.

The social rewards (e.g., credit, respect) that often motivate open source work are undermined. The work is assimilated and resold by the AI companies, reducing the economic value of its authors.

The images, the video, the code, the prose, all of it stolen to be resold. The greatest theft of intellectual property in the history of Man.