According to Yahoo Sports, Hornets
The Timberwolves would be receiving Brad Miller's contract (he's retired), Jerome Dyson and some draft picks. They're obviously interested in some financial flexibility and future assets at this point.
The Hornets are looking for extra bigs, especially after losing Chris Kaman in free agency. Anthony Davis appears to be more of a power forward than a center, so adding Lopez next to him gives the Hornets a lot of quality size inside. And then you have Ryan Anderson and Warrick to provide extra versatility inside. A lot of options there for Monty Williams.
It's a really sensible deal for the Suns too. Johnson was the No. 4 pick in 2010 and clearly has ability, but has never found any kind of place with the Wolves. In Phoenix, he could see a more stable role and more minutes. Plus an extra pick is extremely helpful for a rebuilding team.
Losing Lopez isn't all that bad either as the Suns lean much heavier on Marcin Gortat.
The deal isn't completed and obviously could unravel. But if it goes through, it's a pretty good deal for all involved. Assuming the Wolves utilize what they're getting. Because giving up on the No. 4 overall pick after two years is kind of a shame, especially when all you're getting back is a retired guy, a D-Leaguer and some future picks.