No, I think this will eventually stop. JavaScript is getting more mature. I would not be surprised if the TypeScript syntax will be legacy in a few years, because JS caught up.
Deno will behave just like Chrome or Firefox would: we ignore the checks when running your code. We would have a `deno check` subcommand to perform a typecheck. You could optionally run this automatically before a `deno run` by passing a `--check` flag.
