Re: It'll still work fine - for a while
I suspect that come macOS 10.15, it won't run anymore because Apple will have taken away or blocked something it needs.
Possibly there are already issues in 10.14 Mojave.
Dictation software has to be fairly deeply hooked into the guts of an OS to work at all (let alone well), so it doesn't take much of a change to internals to prevent it from working with some or all applications.
At a minimum it has to send keystrokes to any application, which puts it straight into heavily-trusted driver territory.