TypeScript is pretty good

> Will it catch on? Will our codebase be marginalized if we choose this transpiler?

Even though I despise Angular, when Google announced it was going with TypeScript for Angular 2, I decided adoption probably wouldn't be an issue.

TypeScript is also doing a great job of maintaining compatibility with ES6, rather than creating its own branch. Its goal is to be a superset, not a fork.

> What if we hit unexpected hurdles when using it? What if there are bad design choices that we will suffer from once we go for it?

The good thing about TypeScript is that it can't get any worse than JavaScript. If you're missing TS definitions for a library and need to fallback on a placeholder definition, you're just writing plain old JavaScript again.