The beats from Detox that got released on other albums were really dope so I would think if Dre had a chance to stockpile them on one album it would have been another classic.

The Q-Tip, Common, and Pharrell? album would have been dope as would Helter Shelter, the Dr. Dre / Ice Cube collaboration.

And while I have no idea if the NWA album with Dre, Cube, Ren, and Snoop would have worked but I would have at least listened to that.

Nas and Preemo is a match made in Heaven and I would have loved to hear that album in the early 2000's after Guru died, if Premier was up for that. I'd still listen to it now in fact.

As far as some of the other albums listed, I don't think that the Deck album would have been money. Like another poster said, Deck was great as a partner on a track, but never had a memorable solo track, that I can think of. He was more like Method Man in that regard. Meth was also great when he had a teammate and while he had some nice solo tracks, his solo stuff never impacted me like his group or collaborative work.

Nas and AZ would have sounded great but that pairing never excited me for some reason. At least not to the level some people are.

At first I wasn't thinking much about the Thought album, but hearing his work outside of The Roots clued me into his different flows and styles that he didn't show on The Roots albums. I don't think anyone ever really questioned Thought's skill but I would think that a solo record would have increased anticipation for TFA or least added questions about the lyrical approach to the album; would the album sound like BT's solo stuff or more like his work with the band?