React Native isn't a zero-effort way to port a web app to a native app. It lets you share code where it makes sense, but you're still maintaining separate applications targeting different platforms that each have their own quirks and needs. It's similar to how you can't just port a regular native desktop app by using a different compiler; your business logic may be compatible, but you'll still have to do legwork on top of it.
I'm just saying that "native client" doesn't necessarily mean separate Mac, Windows and Linux ports; furthermore, for a billion dollar company, a native client of _some_ kind isn't an unrealistic demand.
That's fair; although I'm pretty sure they wouldn't be able to have such a consistent and unique look-and-feel with React Native (you can correct me if I'm wrong). It's debatable whether that's a good tradeoff, but it's totally one that some people would make.
well, consistent with what? If you mean the native Mac/Windows/Linux desktop experience, yes, it's definitely impractical to do that with any size budget. But the current Electron app isn't either. But if you want consistency with the web app, I don't see anything difficult about that.
I do wonder if the plugin/extensibility architecture — "Slack Apps" like Github and IMGUR and OpenTable — is the real answer. (Unless I'm mistake and these run on the native mobile apps.)
Consistent across OSes; I haven't really done native desktop dev but it's my impression that the elements you're given can't be customized to nearly the same degree that they can on the web, via CSS.