I guess I don't see how "The competition can just snap their fingers and catch fully up to Tesla on battery output in just a few years anytime they want" is any less Magical Thinking than "The competition can just snap their fingers and catch fully up to Tesla on EVs in general in just a few years anytime they want" that we seem to all agree is untrue.
No, those two are completely different propositions.
1. The statement: "Competition is coming, because the incumbents can create Tesla-killer vehicles any time they want to" is a silly self-contradictory statement, because Tesla has cars that are significantly better than the ICE cars at the same price point. This means, if any incumbent were to create a car
competitive with Tesla, that car would be --
by definition -- significantly better than their own ICE cars at the same price point, therefore it would kill their own ICE sales long before it would touch the Tesla sales.
2. On the other hand, building up Li-ion cell production is not rocket science, there are several companies doing that and there were companies doing that long before Tesla started. Tesla battery tech is better and cheaper, but nobody claimed the other 20 million EV's cells had to be competitive with the Tesla cells. They just have to
exist. That is a much lower bar to pass than making a Tesla-killer EV.
Just like as of today, Tesla has somewhere around a quarter of the EV market world-wide, which means there are more other EVs than Teslas and they have battery cells in them. So assuming that Tesla
only doubles its market share to 50% of EVs and does not take over 100% of the EV market is not "Magical Thinking". Those other EVs will continue to be inferior, have worse efficiency, lower range, but they will exist, just like the e-Trons, i-Paces, Bolts and Leafs exist today and there are people buying them.
The rest of the cell producers do not need to "catch up" with Tesla, they just need to scale up
slower than Tesla does. Currently, the vast majority of cells are
not produced by Tesla but by someone else. So it is Tesla that needs to catch up and take over, which I am sure they will, I am just not expecting everyone else to completely give up.