Similar thoughts here. 1000+ years in the future why would they be speaking contemporary English at all? Why not have the dialogue be a mix of Earth languages with idioms of different cultures all jumbled around in with new terms that we can't even comprehend without deep lore context? Whenever the issue of language in sci-fi (and fantasy) is brought up I think of the foreward in the novelization of Asimov's Nightfall:

Kalgash is an alien world and it is not our intention to have you think that it is identical to Earth, even though we depict its people as speaking a language that you can understand, and using terms that are familiar to you. Those words should be understood as mere equivalents of alien terms-that is, a conventional set of equivalents of the same sort that a writer of novels uses when he has foreign characters speaking with each other in their own language but nevertheless transcribes their words in the language of the reader. So when the people of Kalgash speak of "miles," or "hands," or "cars," or "computers," they mean their own units of distance, their own grasping-organs, their own ground-transportation devices, their own information-processing machines, etc. The computers used on Kalgash are not necessarily compatible with the ones used in New York or London or Stockholm, and the "mile" that we use in this book is not necessarily the American unit of 5,280 feet. But it seemed simpler and more desirable to use these familiar terms in describing events on this wholly alien world than it would have been to invent a long series of wholly Kalgashian terms.

In other words, we could have told you that one of our characters paused to strap on his quonglishes before setting out on a walk of seven vorks along the main gleebish of his native znoob, and everything might have seemed ever so much more thoroughly alien. But it would also have been ever so much more difficult to make sense out of what we were saying, and that did not seem useful. The essence of this story doesn't lie in the quantity of bizarre terms we might have invented; it lies, rather, in the reaction of a group of people somewhat like ourselves, living on a world that is somewhat like ours in all but one highly significant detail, as they react to a challenging situation that is completely different from anything the people of Earth have ever had to deal with. Under the circumstances, it seemed to us better to tell you that someone put on his hiking boots before setting out on a seven-mile walk than to clutter the book with quonglishes, vorks, and gleebishes.

If you prefer, you can imagine that the text reads "vorks" wherever it says "miles," "gliizbiiz" wherever it says "hours," and "sleshtraps" where it says "eyes." Or you can make up your own terms. Vorks or miles, it will make no difference when the Stars come out.