If the response to AI existential threats was "it's too far in the future" then you'd have a point. But usually it's just "AI will obey it's programming" or "AI will never be as smart as us".
True exponentials exist very rarely. What we are used to call exponential is often at most quadratic and even then the trend usually exists only for some limited time window.
I wouldn't dare to make prediction about mankind 1000 years from now based on a relatively short time window of technological growth. There are many huge obstacles in the way.
That seems like a pretty high number when you consider the exponential rate of technological advancement.
1000 years in the future is probably going to be completely unrecognizable to us given the current rate of change in society/tech.