I've not seen the model so I can't make any specific comments - but the numbers look optimistic.
One thing to consider is that Nissan is the largest EV maker in the world and LG getting Nissan to buy from LG instead of from their own JV would be a big win. Nissan thus has a lot going for it when they get to the negotiation.
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A LOT.
The important thing to remember is LG is already a very large producer of batteries and can probably ramp up production of cathodes.
Nissan already has large plants in Japan, US & Europe to manufacture batteries. If Nissan uses LG, they'll probably get the cathodes and manufacture the batteries themselves. Nissan battery factories are sized to produce 250k or so batteries a year.
Scrap Nissan's Leaf battery plant? Hardly