To be honest, any of these two could have a powerful effect on our roster to the tone of a "Rasheed Wallace-to-Detroit Pistons" effect. Sure, they may not be the most ideal, and they sure as hell don't improve our aging frontline, but they are dangerous threats that would give us our first legitimate 20 point scoring all-star (aside from the obvious [LBJ] and borderline [Mo]).
We all know about Vince Carter at this point. He's a 20-5-5 player who was another athletic monster. People know about his stats, but he used to do amazing things with the basketball, showing a prowess for the type of defense that LeBron has been asked to do for us. Did you know that Vince led all rookies in Blocks back in Lockout-shortened 1999? He was very capable of playing defense, but that may not show the way it is now, especially when he's on the wrong side of 30. But he's not just athletic (still good for the guy), but is a very strong support player. He was able to share the ball with two others that demanded it (Kidd, Jefferson) and has helped his teams reach the second round on plenty of occasions. Additionally, he's not just a driver. That was one of his greatest attributes that got him so many points (like LeBron), but has a tendency to hit outside shots too. He's not as dangerous as other players that are known marksmen, but don't underestimate what Vince was and still is capable of.
As for Jason Richardson, his case is a bit more intriguing. On paper, Jason is an identical player to Vince when you start adding up the assists, rebounds, and especially the points. He is very talented with the ball and has shown the ability to hit his shots. But make no mistake, Vince has hit a lot more shots with efficiency throughout his career. For example, throughout Jason's career, he's hit below 70% free throw shooting in 5 of 7 years. But he's still a great player despite not making the All-Star team. But knowing how great he is, we will make it at some point during his career. A poll done during his rookie year had him being the most likely to break out as an All-Star, so there's potential. In fact, I'd say it was his potential that makes him very attractive. He isn't quite the player Vince was, but at this point, Jason is more likely to produce much longer. And he can still reach beyond 23 points every game. He has 3-5 years before he even starts deteriorating (with exception to the ever-common injuries).
But both are extremely good players, are capable of defense (size helps, as does athleticism, and having a defensive coach), and will give us a strong backcourt (if Mo pans out), since they can also hit their jump shots. No one can stick to LeBron on any given night since these two men can both go off on any night as well.
But both have a limit to what they can do. Vince may start falling apart as early as this year, while Jason isn't exactly a spring chicken either. But both will produce regardless. I wouldn't mind either if there was such an option available (but I don't see either one opening up anytime soon). Jason just may be a bit more attractive if only because he has more time left in the tank.
If one or the other were to come here, they would be instant offense. Maybe not 20 + a game, but at least 16-18, similar to the Celtics with Ray, KG, and Pierce. But other players would defer to these two, so they would get more shots as a result.
That's the gist about both of them, but neither the Bobcats or Nets are giving them up currently, with them being the "franchise" players. Never say never, but wait and see if one or both teams collapse (I ain't holding my breath because I already like what I see and want to give that a chance...).