Where does Ember stand in supporting Web Components? They are now pretty stable and supported by all major browsers. Can they be used in the framework today? Or should we wait? Also, will they eventually make traditional Ember components unnecessary?
You can use web components in an Ember app today. If you have a custom element defined and use it in a template, it will work.
I don’t see them replacing Ember components (or React components, or Vue, etc) any time soon. They have a lot of missing features relative to framework components.
There is also the question of whether you can package Ember components as webcomponents. It’s been done in GlimmerJS as a technology preview, but hasn’t made it back into Ember yet as a supported build target. It’s not very hard to do by hand, but the main issue is making an optimized build of Ember that only contains the things you need for your component and nothing else. A lot of current work is bringing that closer, mostly improvements in the build tooling and the package organization.