Strongly disagree. We (Ionic) built our new version directly on top of Web Components and they are certainly a thing for us and our users building real apps on top. Plus, they are a huge reason why we now support React and Vue and plain JS.

Frankly, this has been transformational for our project and for our business. I'm completely sold.

One problem with the WC debate is people constantly compare the raw Web Component collection of APIs to a framework, when in reality, you'll add in libraries or extras on top of your Web Components to get similar functionality (like Stencil: http://stenciljs.com/), but you'll likely not build apps with them as much as you'll build components to share with others.

In that sense, the killer app for Web Components is actually Design Systems, not SPAs.

I disagree with the idea that Web Components replace your framework, however. They solve different problems! For Ionic as a cross-platform Design System, they are a major asset.