The article alludes to two technical problems. One is density altitude; hot air is remarkably less dense than normal air. Redding is at 500', when it's 120°F out that's like 4400'. Not impossible for an ordinary helicopter but as the pilot says, you can't lift as much. The other problem is the electronics overheat.
Both seem like fixable problems: bigger engines and more heat-resistant electronics (possibly with active cooling). But you have to build for that. It's only going to keep getting worse.
(There may be a third problem with engine performance, I don't know about that.)
Bigger engines won't help overcome lower air density.
First, bigger engines mean more weight, which will mean more power required to lift the base weight of the aircraft. Second, the problem isn't (ironically enough) pushing the blades through the air, it's the limit of each blade's ability to generate lift. Third, they can't just spin the blades faster, since they're approaching the speed of sound at the tips as it is. Breaking that speed causes a whole new set of issues to design around.
It's a balancing act, and the weight/lift/capacity/payload balance has already been struck in many cases. Will we see new designs? Perhaps, as they become economical due to climate change.
Both seem like fixable problems: bigger engines and more heat-resistant electronics (possibly with active cooling). But you have to build for that. It's only going to keep getting worse.
(There may be a third problem with engine performance, I don't know about that.)