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.
Regarding "doing the Microsoft classic" whatever that means... I don't believe in judging a company by what they did in the past. They should be judged by what they actually do now and in the future. So far, they haven't done anything bad. And anyway they've been good stewards of recent products that they've taken over (GitHub for example).
As for TypeScript itself... well my opinion is language choices should always be done on a case by case basis. So far I have never personally encountered an individual case where TypeScript is the best choice. They do exist though, so I won't hold it against anyone if they choose to use it.
Ehhhh... considering what they did to the .NET stack recently (removing dotnet watch from the open source builds to bundle it with Visual Studio and only reverting due to the huge community backlash), I think at least some cautiousness would be warranted.