"They don't really have any huge untapped resources to expand into"
Howbout 270 million tonnes+ of high grade Spodumene!!!. 20+ times bigger than Mt. Cattlan.
I'd say that will keep them busy for a few years and has plenty of room for expansion!!.
Especially if you consider they may start shipping Lithium salts around the globe as a precursor to Hydroxide production. And this is likely to happen earlier than 2024/2025 when a lot of the GXY Brine will come online.
GXY and PLS are 2 very different beasts and no need to compare them. They are both exceptional companies and winners. Both will be absolutely massive and huge successful players in the Global Lithium market.
I own a heap of both (slightly more GXY actually) and they are both like my children.
Please don't force me to pick a favourite child as I love them both the same