Obviously, there is no objective wrong/right here, as only the future can tell. My subjective experience tells me, it will be that way.
There is no need to context-switch. Just accept Javascript as part of TypeScript, because it really is. The argument is clear: TypeScript drastically reduces the amount of errors you will be making when coding, and the amount of time you need to think about stuff that is really trivial.
The rule of thumb on how to do this is also simple: Keep your types simple, use them to make your life easier, not more complicated. If you cannot model something simply using types, don't try to do so, just use the dynamic typing escape hatch that Javascript provides.
I'm just explaining to you how it plays out when a business is deciding whether or not to use TS at all. Mistakes and errors are checked for by linters and unit tests automatically in the background so that's not a benefit anyone cares about. The liability of having to find coders that want to work on your TS project decreases potential candidates and makes hiring more difficult. Large organizations can deal with it cause when you have 500 engineers on staff you can find 50 that will use TS for you. For smaller orgs it's a pain.
These are concerns that will arise in some organisations, for sure. Personally, I don't have a need to work together with people who cannot be bothered to learn TypeScript. A nice type system is something you really want, and which improves code quality. No need not also to use linters and unit tests. These things do not oppose each other, they work together nicely.
There is no need to context-switch. Just accept Javascript as part of TypeScript, because it really is. The argument is clear: TypeScript drastically reduces the amount of errors you will be making when coding, and the amount of time you need to think about stuff that is really trivial.
The rule of thumb on how to do this is also simple: Keep your types simple, use them to make your life easier, not more complicated. If you cannot model something simply using types, don't try to do so, just use the dynamic typing escape hatch that Javascript provides.