The discussion to move Deng, from my perspective and most people here, has always been to establish a different (not additional) piece to support Derrick for the next 5 years of years his career while changing the way the Bulls function or clearing cap to do so. The reasoning behind the suggestion was simple, though the Bulls could defend any team in the league they lacked offensive efficiency and bench production to out-score their opponents. This season has been a very similar case-study with the GLARING omission of Derrick Rose missing EVERY game.
The other two teams you listed are in COMPLETELY different situations. Boston was looking at the big-three as the "old three" and could have very easily pushed reset if KG decided he wanted to see what else was available in the league and NOT retire as a Celtic. Pierce is now the first of those players looking at the same situation - take a discount and stay in Boston or go somewhere else. On top of that, Ainge is put in the scenario where Pierce may still have value as an veteran player with some (not much) mileage in the tank and a large expiring deal. It's not far fetched to shop Pierce at all. The concept of trading Rondo isn't nearly as absurd as you suggest considering the consistent rumors surrounding how Doc, Ainge, and Rondo interact, but there's no denying he's the best athlete on that Boston squad and likely not going anywhere without stellar returns.
Dwight and the Lakers are a match made in heaven (or hell). If Dwight can't find a way to work out his differences in LA, I expect to see the team change around him. Yes, he's on the verge of destroying another team but it's sheer idiocy to think of Dwight as the asset leaving the Lakers when Gasol and even Kobe are still there.