The profits won't be minimal, though, will they?
I mean - they aren't going to be on a breadline for having a disc version. After 13 odd years isn't GTA V still one of the most profitable games in existence? GTA VI will easily replicate that and beyond.
Not having a CD isn't because of profit margins, really, it's exactly as other posters have said. To ensure that future copies are bought from source and not from the 2nd had market and to throttle lending.