So, in other words, the not-so-really-good IT professionals should commit themselves to chasing the next rainbow, which this author has asserted is software development. I don't see how this is going to benefit anyone involved.

The people who chased the IT promise of huge salaries in the last decade or two are already jaded because those salaries came with an an expectation that they deliver as much value as the superstars. Given the oft repeated statistics and horror stories and such, I'd suspect most of them struggled to generate even as much value as their employer paid them, let alone actually be profitable to employ.[1] So they entrenched as best they could, and tried to make themselves valuable by hoarding knowledge and trading political capital. This worked until the knowledge they hoarded became irrelevant, because better, easier technology became directly accessible to the people the IT department supported. The technology certainly didn't require no support, but it required much less, and the best people in IT had already learned about it because they actually like their profession and spend their own time being curious.

Ironically, I've noticed a tendency for people in IT to be really staunch neo-luddites; the same forces that made them valuable are now making them irrelevant, and they were too narrow-focussed on their own walled garden of knowledge to notice that the process never stopped. So, now they are waving at barn-doors. I'm sure they'd have shrugged their arms at elevator operators when those became fully automated.

So, what now if they flood into the world of software development? I suspect one of two things will end up happening. Either they'll be met with a wall of high expectations that won't even let them in, or they'll go through another cycle of entrenchment followed by irrelevance, with the same knee-jerk reaction of trying to blame technology for continuing to advance. It will probably be a blend, where some places will set high expectations and refuse to let anything but the really good people in, and the rest will suffer from entrenchment of the workforce.

So here's my tl;dr point: it's not about the IT vs. developer delineation. It never has been. In fact, a lot of the people who start these ISVs and write these small modular apps have to play both roles at once. It is about the passionate and capable people vs. the one's who chase rainbows and try to ride along long enough to get some sort of windfall. The latter has never been a sound personal economic strategy; the only difference now is that technology iterates rapidly enough that the not-so-really-good get found out a lot sooner. If anything, I think that will be the next decade.

[1] Either that, or all of the statistics and stories are crap, but I would believe that more if they weren't repeated by people who have had decades in the industry.