Provocative FP, but I think you're mostly wrong and lacking in the kind of insight that will lead towards any solution. Most obviously, the Democrats are not going to solve anything. I think we are actually in a situation where too much change has become a key problem, so controlling and even limiting the changes are crucial. I sort of hate to say it, but I think the Amish may have it right when they consider newfangled ideas carefully before adopting them. (The Amish religious stuff mostly seems bogus, however...)
As regards the monopoly problem, I think the best solution approach might be a progressive tax on profits where higher degrees of monopolization result in higher taxes on the associated profits. The "natural" path to higher retained earnings would then be for the monopolist to divide itself into honest competitors. Three metrics (plus your ideas) could be used to detect the monopoly: (1) Limited customer choice and too few meaningful options, (2) Inability of wannabe competitors to enter the monopoly niche, and (3) Lack of alternative employment options for people working in the niche. But "We can't get there from here." Certainly there are no politicians who are trying to lead in such a direction.
Returning to this story I think the actual key is in the deltas. Yes, Amazon does need engineers, but profit maximization calls for keeping ONLY the engineers who can produce the highest rates of profit increase. All less productive engineers are just slowing things down. The delusion that Amazon is now suffering from is an idea that AI (and related IT) can be used to replicate the work of the delta-maximizers all over the place.
The reality is different and I expect to be amused by the implosion--even though I will also probably suffer from some of the collateral damage.