I agree with your general view. However, you make a common...

I agree with your general view. However, you make a common mistake by pretending that all your points contribute to the same conclusion. Some of them necessarily cancel out:
From a technical point of view, lithium is the most effective chemical element for ion-batteries. If you substitute lithium by other element (e.g., sodium) you are losing performance (more weight, less energy density, etc.). So the only reason to employ other elements instead of lithium are economic (a too expensive lithium price). If you forecast lithium price to remain cheap (your point 4), then the EV industry won't replace it by any other element (point 5). These assumptions you make won't work together to the same conclusion. Either lithium remains cheap and its demand for batteries will grow, or its price will go higher before its demand decreases due to its substitution by other elements.
If you make a survey on current research and advances in batteries, you'd notice that the only justification for developments on batteries employing other elements is that lithium is becoming expensive. But no research on lithium-free batteries is proclaiming superior performance. On the contrary, most research is focused on improving lithium batteries. And it seems that they will employ more lithium in the future.