Well it wouldn't be difficult to avoid that fate these days, would it?

I assume they will be using TypeScript, async/await and so on. It's a pretty great language to write in, certainly comparable with C# in terms of maintainability IMO. And a later tweet clarifies that it's being used with React Native to create an actual native app rather than force a webview everywhere.

Everyone has a gut reaction to news like this, but it sounds good to me, and the reasons for doing it seem pretty clear.