IMO the promise of container queries isn't that breakpoints will go away, but rather that breakpoints can emerge from the bottom-up composition of components rather than top-down from your CSS framework or Tailwind config or whatever.

You're still probably going to want the left sidebar of your multi-column layout to collapse behind a menu on narrow viewports and abruptly appear when the viewport width gets to >= n [0]. But it's conceivable that the value of n emerges from some constraints you specify (such as the minimum desired width of the sidebar and the main content column), instead of being chosen upfront from a small list of predertmined breakpoints.

[0] E.g. https://tailwindui.com/components/application-ui/application...