After 3 decades of being a die-hard Kings fan, I can safely say that I, for one, would never follow the team again if they trade Cousins this way.
However, no matter how the poll turns out, I predict that most fans will end up being "Stop following the Kings until they start winning again" kinds of fans.
I can easily imagine it playing out like this:
1) Cousins is traded for middling vets and picks. The Kings organization puts on the massive PR front of making the best of a tough situation, and Cousins puts on his act of "I just wanna go where I can win". Both sides inexplicably survive this crapstorm.
2) The Kings somehow start winning, even with the lesser talent on the team. Everyone is surprised (except me, knowing how the NBA as a business works), and magically the team will still be over .500 when the new arena opens in 2016. The answer (for people in the future wondering how it's possible) is that I'll let y'all in on a little secret - the Kings haven't wanted to win in YEARS. Once they want to win, and the NBA is copacetic with that idea (new arena and all, gotta point to a successful city ponying up the money for their jewel arenas) it's really not that hard to eke out enough wins to be "a winning franchise" but not make much of a dent in the playoffs. There's plenty of room in the NBA to allow for that kind of "success" to assuage the fanbase and stoke the fires of business.
The Kings fans will stop their howling once the team starts winning (because as I predicted back in December when they lost to the Lakers, the fanbase is so sick and tired of losing they will take ANY winning, they're so desperate, which caused the pressure which led to the kneejerk firing of Malone, which led to...). They'll express their amazement that the team "isn't so crapty" (in the immortal words of Major League) and the relatively meaningless late-season wins will placate the starving fanbase enough to get excitement back in the place just in time for the new arena.
3) The one part I can't guess is just how successful will Demarcus be in this future.
The NBA still hates him, and he still lacks the personality and wiring to play along with their bullcrap.
If he lands on a team that doesn't have much talent to compete, he's going to have a miserable time. He may well be talented enough to cause a team (that's actually trying to win) to succeed, but with the kind of control the NBA (thru the refs) has on his career, he could go either way.
Really, the Kings have much more prospects to succeed in the near future - Demarcus would be leaving at the exact wrong time. Why live through these 5 years of HELL, when the relief and balm of winning is this damn close?