I don't think a sex scene would ever be needed. We may see one or two, we've pretty much seen as much of it as we can on TV in the previous shows and movies with Kirk, Riker, etc. But I see it as more of the freedom to not be forced to hide nudity. A doctor may need to rip open a girls shirt to treat her wounds. We could see a Betazoid wedding in all it's glory. Pon Farr.
As well as getting past the language restrictions. I could see Picard yelling "I'm tired of your shit Q!" Or Data discovering the word fuck and using it in completely inappropriate situations.