Specifically, do you worry that Microsoft is going to eventually do the Microsoft thing and horribly fuck it up for everyone? I've really grown to appreciate the language itself, but I'm wary of it getting too ingrained at work only to have the rug pulled out from under us when it's become hard to back out.
Edit: not really "pulling the rug", but, you know, doing the Microsoft classic.
I don't think there is any merit to that concern. Not only is TypeScript FLOSS, Microsoft also has an excellent track record developing high-quality programming languages and tech stacks. Take for example C#. It's been around for over two decades and if anything it's getting better by the release.
I understand the rationale behind the concern, but there is also a factor of mindlessly parroting cliches.