To me it's far more likely Sacramento gets Ty Lawson and Kenneth Faried to surround Demarcus Cousins than it is the Celtics get Lawson and Cousins. Sacramento has absolutely no reason to deal Cousins unless he demands a trade, and Sacramento has more upfront desirable assets to offer Denver than the Celtics have to offer Sacramento at the moment (They have an actual lottery pick as opposed to potential-but-not-for-sure lottery picks). Not to mention George Karl would love to get players that he has worked with before. Especially players who were not happy after Denver fired him.
http://larrybrownsports.com/basketball/denver-nuggets-fire-george-karl-kenneth-faried-and-ty-lawson-are-baffled/190725Faried and Lawson wouldn't be ideal but they would be better than what Sacramento has now. Them, Cousins and Gay would make an entertaining core even if the west is a bloodbath. Denver is on the pathway to rebuilding, and getting Sacto's pick + young talent would help them build a better future.
I could see a deal like this going down:
Sacramento trades #6, Ben McLemore, a future top-10 protected pick, salary filler like Darren Collison, Jason Thompson (Denver could market those guys for more expirings and picks to teams trying to win).
Denver trades Lawson and Faried.
Yeah not exactly on topic but the point is thats more likely to happen than Cousins coming to Boston. The Celtics have a lot of assets to trade but there's no guarantee that those picks are going to be good.