ASX: TAW 2018 Lithium Pricing - US $1,000/T, page-36

Settle down. It depends on what the CR is for. Your "massive dilution" statement is meaningless (or at least the bad connotation you attach to it is) if that CR cash is used to grow the business. In your own example of raising $1.5B to reach a $2B market cap, those funds would actually be used to more rapidly grow the company to a $3B or $4B business.
Dilution? yes, mathematically. Bad for shareholders, definitely not.
If the cash is used poorly, and the business doesn't grow or accelerate as a result of that CR, then yes that dilution would be bad for shareholders.
I trust the GXY management to make best use of the CR cash (i.e. accelerate growth to ultimately improve the value of the business), so it (the mathematical dilution) doesn't bother me at all.
So, you are partially correct, but IT DEPENDS!

IMO: we (the world) are going to need a lot more lithium mines/operations to come online in the next decade, so your concern over "another" coming on line in 2018 or 2019 and increasing supply, is not an issue at all. We won't be able to keep up for a long while yet. Transition of the global vehicle fleet to EVs over the next say 30 or 40 years = +50 new mines required! ....exponential growth upon the tipping point... Buckle up for when that happens.