Scanning negatives — where quality is actually lost
DarkroomUsually not in the scanner's resolution figure.

Resolution is rarely the limit
Most scanners resolve more than the negative holds. What limits the result is focus, film flatness, and dust — none of which appear on a spec sheet.
Flatness first
A negative that bows puts part of the frame outside the plane of focus, which reads as softness at the edges and gets blamed on the lens. Holders that tension the film fix more apparent sharpness problems than any resolution upgrade.
The orange mask
Colour negative film has an orange base that has to be inverted and corrected. How your software handles that decides most of what people call "the scan's colour" — far more than the scanner hardware does.
Dust
Every minute spent on dust before scanning saves ten spent retouching after. There is no clever step that replaces this one.