Dark roast does have more caffeine per gram, because there are more beans per gram, because beans become lighter as roasting continues and more CO2 is released.
Counting caffeine per bean indeed darker roasts have less caffeine, but it’s a tiny tiny difference, so the effect of the whole bean getting lighter wins out when measuring caffeine per weight.
As for decaf, all methods affect taste. Swiss Water isn’t inherently better. Water is a chemical solvent. Is this an ad?
Tldr climate apocalypse for the coffee plant might shift the market towards alternative plants. While technically true that coffee plantations will struggle in the coming years, this just means higher prices and worse average quality off the shelf.
A bit of nothing news, imho.
Coffee alternatives like rooibos are already here and the market is very resistant. Cheap coffee drinkers are irrationally attached to the bad taste they feel nostalgic for. Fancy coffee drinkers will absorb the higher costs without looking for alternatives. It’s only the tea-adventurous coffee drinkers that care about these innovations, usually due to caffeine consumption restrictions which is also a disputed market because decaf coffee quality is improving.