If the Knicks land Melo, they won't need a third superstar to compete for a championship. Yeah, they'll need other pieces like a defensive center and a point guard, but "who wants to come win a title with Amar'e and Anthony" is a better pitch than anything that happened last summer.
Frankly, I'd trade everything not named Amar'e to land Melo because the model for team-building in the NBA has changed. It's a lop-sided deal in that case, but I can find players who are just as good as Landry Fields or Gallo or Mosgov or Chandler or Felton. If you compare that to Anthony, the only scorer like him that's come out since he was drafted is Kevin Durant. Add that to the fact that he's only 26, and that opens at least a 4-5 year window for the Knicks to compete in until Amar'e's done. These days, you put the 2 or 3 superstars together and let the role-players follow. The Lakers did this unsuccessfully in 2004 with Kobe and Shaq, but since then, Boston, LA and Miami have used this formula successfully and this is what the NBA is moving towards.
Denver hasn't said yes to this package, but if you have to give up Gallo, Curry, Chandler, Felton, and Anthony Randolph for a first-rounder plus you get Billups in return, you have a starting lineup that looks like this...
Billups
Fields
Anthony
Amar'e
Mozgov
Add that to Williams, Walker, Ronnie Turiaf, Toney Douglas, and then assume the Knicks bring in Earl Barron as reported, and that's a pretty good team without even considering what you get back in filler. Yeah, it could use a backup point guard and it needs help with a defensive center assuming that Mozgov doesn't pan out next year, but those are the same problems we have now anyway and the lineup with Melo is better.