Amazon is under almost zero plausible threat of monopoly issues outside of niche categories like e-book readers (which would end in fines rather than traditional broader anti-trust punishment).

Amazon will never acquire a greater dominance in retail than what Walmart had at its peak, and Walmart was never under serious anti-trust threat. Walmart also once owned an extremely large hauling business (eventually mostly sold off to Berkshire Hathaway), and operates a large private-label Great Value brand.

Not a monopoly but Amazon Basics products are copies of Amazon's best selling products at a much cheaper price. This makes third-party vendor competition pretty harsh. I can buy a Rain Design mStand Laptop Stand for $40 or buy the Amazon clone for $20.

When Walmart, Target and Fred Meyer no longer exist in WA state would be a start