we've also seen games announced with no platforms before like Starfield and Elder scrolls.You can announce exclusivity to platforms without announcing consoles. We’ve seen it many times, we’ve also seen a long trend of behaviour where if MS doesn’t immediately announce exclusivity (once the title is announced) it is likely not fully exclusive.
If you announce it's coming to the xbox platform many will assume it will be on the series consoles and if it gets reported that way it will be very difficult to announce later on that its only next gen xbox consoles.
We will just have to wait and see what happens. Perhaps we will hear more during the e3 time frame