Just to elaborate a bit further to help fellow sojourners:

1) I use Webpack to bundle, still practically indispensable.

2) Redux state management. I use Redux-ORM to denormalize data but it has its own quirks.

3) Shadow DOM is on by default (both a curse and a great thing), which can be a problem with styling because your global CSS can't penetrate everywhere. What I do is have lots of CSS utils files (ala TailwindCSS), and import the utils as I need on demand. Drawback: Browser is parsing a lot more CSS than it needs to, as each component imports it's own CSS utils. Happy to hear about other approaches, but the browser really didn't break a sweat.

4) With Shadow DOM, you can use <slot></slot> to compose components.

5) Routing, see the starter kit for patterns, essentially it's a router pattern, not a router library.

6) DOM event bubbling is very useful (CustomEvent), I even threw in a small Pub/Sub library somewhere for sibling communication

7) You could use some sort of DI (dependency injection), currently using di-ninja which seems a bit overkill

Essentially, nothing much changed. Use the browser. Use JS. Use patterns. Use libraries as you see fit (watch that bloat).

"Stick to patterns, not libraries" - Such a simple statement, but concise as hell. It's whats been my mindset, but I haven't put it to words. Like normal DOM event bubbling is going to cover lots of use cases. When it doesn't, an event bus is crazy simple to write. A centralized data model can just be a static module. Need observables? Easy to write a simple one - otherwise there's likely a bazillion of them on npm. Not that I've used it, but it's not like Redux or MobX are restricted to React either

Right... why use an existing framework when you can just build your own!