Earlier quoted context omitted.
> > Saying everything is so integrated that it can't possibly be decentralized is basically proof of monopoly. > This doesn't matter from the standard of antitrust law. What most fail to grasp is that being a monopoly is not illegal. It's only illegal to use monopoly power to harm consumer welfare. Citation needed? I thought, in the US at least, that the government will go after you if you use your monopoly powers to…
It depends on how the Justice department feels, to some extent. GM in the 50s and 60s actually kept an eye on their market share, and sometimes would kill/cutback projects or products that may have threatened going over a certain percentage (around 60%, IIRC.) At that time merely going over that number would have been enough to start an investigation. Some would argue though that back then DOJ 'cared' more.
Given the current makeup of the court, it seems extremely unlikely that the justices would overturn this precedent.