It's only one game, but if Anthony Davis and DeMarcus Cousins don't work together, Al Horford and DeMarcus Cousins certainly wouldn't have.
Defensively they were definitely a questionable fit. I don't see any way Al and Boogie couldn't work together offensively, though. They're two of the better playmakers and passers in the league from the big position, probably top 4 or 5 alongside Griffin and Gasol. And with both of them extending their range, I don't see any way we wouldn't have been even more elite offensively with them.
A lot of that is going to depend upon how Gentry uses them, too. From what I've watched so far tonight, he looked clueless how to pair them together out there, which isn't really unexpected given its their first game together. He hardly ever attacked the mismatches on the bigs, and he's seemingly really hurt Davis offensively with making him so perimeter-oriented.
Brad does an excellent job with exploiting mismatches offensively, especially on the post-up, so I can't imagine that he wouldn't have them humming offensively. But certainly defensively they could've presented a problem together.