Wasn't Pharrell going to be on the 20 YO album until JD or someone else scrapped his stuff and went in another direction? Pharrell and Janet should have done something ages ago (2000-08), but he's still popular and makes bops so I wouldn't be opposed to a track now.
I think the main problem with Damita Jo, 20 YO and Discipline has less to do with the fact that she was working with different people, and more to do with her lack of input, inspiration and the amount of different people she worked with at once. If Janet decided to have JJ/TL, Babyface and, say, Pharrell produce Damita Jo, and she had something more interesting to talk about, I think we would have still gotten great stuff on par with her classics. I think a smaller team works well with Janet's artistic process.
Well, J. Lo did a song with Cardi and performed it at the BB awards in May. I haven't heard it since and I don't think it's made a dent on the charts.