Here's the issue with a potential trade for Melo.
1. The Knicks may not want to trade Melo to a division rival, especially since they are run by Phil Jackson who I don't think wants to help the franchise he's battled against in the past. I agree the Celtics have a relatively decent package if the Knicks are aiming for a trade that will help them rebuild, but because the Celtics and the Knicks are in the same division, I don't see the Knicks trading Melo to Boston unless its an offer they can't refuse. To put it into a better perspective, the Lakers had a pretty good package for Demarcus Cousins with the #2 pick (Russell), Randle, and Clarkson, but the reason why the Kings didn't pull the trigger is because they didn't want to help the Lakers and have to face DMC 4 times a year. The Knicks might think the same if they were to deal Melo to Boston.
2. Melo has a no-trade cause, which means he has all the negotiating power on his side. He can choose where he wants to go if the Knicks trade him. To me, the reason why he re-signed in New York is not because he wanted to stay a Knick necessarily but so that he could make the most money and decide which team he wanted to go to next in case things were to go wrong in NY. If he is on the market, I'm pretty sure he won't choose Boston. The Celtics don't have much to offer to Melo currently as far as what he wants. Melo wants to be on a team that is good, has a great nightlife, and/or has a buddy on his team. The Celtics don't have any real stars on the team and if they traded for him, they more than likely would have to trade the guys who could become stars, like Smart, to get Melo. If Rondo was still here, I think Melo would give it some thought, but Rondo isn't, and I'm not sure CBS wants a diva on the team. I think the teams Melo would most likely say yes to are LA, Houston, Miami, Chicago, or Dallas off the top of my head.
3. I only want Melo on this team if I know other guys are coming too. Melo alone on this team isn't enough. It's a step in the right direction, but the Celtics need more than just him. If that doesn't happen, then the Celtics will be saddled with Melo's ginormous contract that will more than likely be an albatross around year 4 or 5.
I would welcome Melo, but I'm not too confident in him coming here, and if he does, I think the Celtics will need more than just him to be a contender.