Interesting point. Lets do the numbers. Supposedly desalination is 86.55 million m3/day (https://iwa-network.org/desalination-past-present-future/). 1m^3 is 10^3 kg. So 8610^9 kg desalinated water, I dont know the conversion rate, but lets say rougly 110^11kg water from sea pumped. Divided by 5e6 we have 2*10^4 kg/ day. 20 tons of lithum per day. Sounds a lot. That's roughly 8000 tons of lithium per year. Worldproduction is 80000 tons per year. https://www.statista.com/statistics/606684/world-production-... So while not insignificant it doesnt seem a game-changer. (I might have miscalculated a factor of 10 somewhere, probably..)