It's a long shot, of course, but it COULD happen given certain conditions:
1) Orlando is having an awesome season being a top 3 team in the east. Ryan Anderson has a monster year averaging 18 ppg, 8 rebounds, 40% 3pt FG. Dwight is happy and while receiving the MVP trophy at the Allstar game he says he is staying with the Magic.
3) Deron Williams is recruited by DH and is willing to play in Orlando in order to win.
4) Deron tells the Net he is leaving after the season
5) Andrew Bynum stays healthy and have a great year.
So now the Nets have to choose: let him walk without getting anything or trading him for whatever they can get. No team would give them good assets if Williams is not committed to signing with them, so they would have to trade him to Orlando for whatever we have to offer.
Of course it's not that easy, the Nets could always play chicken with Williams. If they don't trade him to Orlando he would lose millions signing for the midlevel exception as a free agent (something he won't do, of course).
But they know they are losing him anyway, so they better get something in return. What else is in the market? Basically what it was offered for CP3. The Nets would have no interest in Houston oldies like Scola, in Pau Gasol or Amare. They need someone to build around for the next years. Andrew Bynum would be ideal, but the Lakers are not trading a young 7 footer which averages (in this scenario) 20 ppg, 15 rebs and 2 blocks, for a PG. You don't trade big for small. Are the Warrios willing to give up Stephen Curry for a 3 month rental of Williams? I doubt it.
So then, Orlando could offer Ryan Anderson + stuff for Deron. If Ryan posts 18-8-40% 3pts during the season this deal is not worse than Lopez for Howard. Anyway, the deal hasn't to be fair, it just have to be the best deal AVAILABLE. A young big guy who can shoot the 3 and rebound is a great asset. And we all know how the Nets fans appreciate players with "potential".
But then the question would be: if Orlando is a top 3 team in the east, would you disrupt the chemistry, and send an almost irreplaceable young talent (Dirk and not many more can shoot the 3 and rebound while being 6'10 or taller) for a smaller player with character issues?
I guess I would, the possible payoff is worth the risk.
1) I am not saying this can happen today. IT CAN'T.
2) I am just saying that if a long list of things happens this year, which is highly unlikely, then, and only then we COULD have a chance to get Deron.