Exactly. I doubt most of the ChromeApps that exist today were made for ChromeOS. They were made because it was an easy and straight forward way of making a webapp on the desktop. Now, as OP mentions, everyone is moving to Electron and NWJS, neither of which works directly on ChromeOS.

The only upside I can see is that CrOS is soon going to support running Android Apps which may save it, but even then... Maybe they'll figure out a way to run Electron/NWJS apps on ChromeOS?