Do you know something we don't? Last I heard, no decision had been made yet on Deep Space Nine
No, sorry... I didn't mean to suggest that. I was just extrapolating. I have no special knowledge of CBS's plans right now. But come on, they're gonna have to do it eventually. They have all the 35mm assets at their disposal (and we now know the CG models and scene files are out there too in the possession of the original VFX supervisors). If CBS doesn't upgrade the two other 24th century series, they can't resell them for streaming, digital download or broadcast.
Also, CBS can just deduct whatever the cost of remastering these series is as a business expense. CBS Digital is owned by them, after all! It gives them steady work for essentially a decade!