According to TVShowsonDVD.com, Season 4 of "Night Court" will be available this fall, most likely exclusive to the WB Online Shop. It didn't seem to be clear whether these would be MOD discs, or actual manufactured/pressed sets.
Apparently this will be the new reality for releasing older TV shows, as the article notes that many major retailers are resisting stocking "retro" titles.
I know I never saw S3 at either of the two nearby Best Buy stores, and I think Walmart only ever had 1 or 2 copies in stock before they gave the shelf space to a different title.