The NBA isn't a point guard's league, it's a swingman's league now.
That being said I agree with the above assertion. If we gut our team and it doesn't lead to a championship, we're left with little to improve on and are stuck with that same team forever. Amar'e + CP3, while awesome, does not yet guarantee us a title. And if we don't get a title, then we've wasted the time.
Amar'e + Melo + CP3, on the other hand, is as close to guaranteeing a title as you can come, so I say we hold out on that one. Plus imagine if either Anthony Randolph or Danilo Gallinari becomes an all-star caliber player, then we might not even need to get another superstar via FA or trade