> 2) already economically viable, or projected to be economically viable within 2 years by actual process engineers with experience in scaling up chemical/electrical plants to industrial size

Why 2 years?

Even though I'm expecting the current approximately-exponential growths of both PV and wind to continue until they supply at least 50% of global electrical demand between them, I expect that to happen in the early 2030s, not by the end of 2027.

(I expect global battery capacity to be between a day and a week at that point, still not "seasonal" for sure).