First of all I really love the show, been a listener from episode #1.
I have a response to JavaScript replacements being irrelevant with ES6 standard. This is not true, have you heard of ES7 (and in the years to come there will probably be ES8, ES9,...)? Why do we have Babel and a wide range of different languages that transpile to JavaScript? Different browser vendors can't and probably never will keep up with the latest standards (hello fragmentation) and this reason alone will guarantee these languages/transpilers to stay relevant (Babel).
As for Typescript it is advertised as a "super-set of JavaScript with types" and it really is just that. You have an optionally statically typed JavaScript language and the fact that you have static typing is a good enough reason to use it (Ruby is considering adding static typing). If you have 300 LOC (Lines Of Code) then this probably doesn't really matter to you. But if you have a project with 100k LOC (or more) you did not write or have written long time ago... good luck changing that without breaking it :), and to make things more fun you can find the error only during run-time at some rare case (even if you have tests for your code). Static typing can greatly help you with that as it can point out the problems at "compile/transpile" time, reducing the time of catching and resolving BUGs. And also static typing is much more clearer as what the programmers intent was in the first place (After all we are writing code to be readable and understandable for human beings).
Now to be fair introducing a new language does bring overhead and all the JS transpilers are still JavaScript in the end so you need to know both technologies under the hood. But to be also fair if you are writing pure JavaScript chances that you are using Babel are probably 50% because of that new feature you need to use (async / await). So in the end you still have overhead be it Babel, Typescript or what ever you prefer :).
That's my two cents guys, keep up the good work and send all the hate mail to Alan Jude... joking ;)