Nvidia could only fuck them over like that because they were able to produce their own boards: If they have to rely on board manufacturers to sell their chips, they have to be nice enough for board manufacturers to actually bother doing that.
Margins wouldn't change. GPUs are brand sellers, OEMs would try to make their margins on other products. E.g. if Asus were to stop producing graphic cards for Nvidia, their mindshare would plummet
...and market share going to other US companies would hurt that interest in what way exactly?
You are the one bringing up market share into the discussion. I haven't said anything about Nvidia losing market share hurting US interests
AMD shmahemde. There's a gazillion US startups in the space which could make it, or not, and/or be bought up by AMD or Intel, both certainly have their eyes and products on the market. The US' national interest is hurt by nvidia's unfair business practices limiting bringing innovation to market.
You're acting as if they're the only actor in the market, but there is competition from multiple sides. You don't dismantle a company purely on them having a dominant position.