Good article, but I don't agree with many points there - like JS with CSS can do UI wonders. I think the same can be done in Flex/Flash for a fraction of code.
Adobe AIR is not 'yet another UI toolkit', you have to learn, it can very well become an ancillary tool to Flex. In fact, the idea there is you can keep the same UI, same components, and changing the container from web to AIR. Of course, you may have to switch how it talks to your backend, but its a great way to create an online/offline version of the same app, reusing most of the same flex codebase.