Here's the thing.
The twist and the basic concept works fairly well, within the film, largely due to Kingsley's performance.
The problems with the approach are twofold.
One, the actual reveal of the twist is somewhat lazily executed well and wasted the potential of the concept itself. Seriously, they have Tony just STUMBLE onto Trevor already not being The Mandarin? Why not have him IN the guise of The Mandarin when Tony encounters him, trying to put on a brave face and have a "supervillain" confrontation with Iron Man or Tony that rivaled Tony/Loki in THE AVENGERS, and then, in the middle of his scary megalomianical terrorist bit going "Oh, I can't go on. You've got me. It's all a ruse." etc. Not that dialogue, obviously, but it would be much better, with more tension, and more impact. By the time Tony finally encounters Trevor, the audience has figured it out, and it loses some of its impact in the way its presented.
Two, the overall concept simply doesn't work as well as what could have been, and arguably should have been. There's no reason The Mandarin couldn't have been treated more seriously, and been a blend of his classic and more modern incarnations, and had better interactions and connections with Killian and AIM than being a puppet.
And worse, the one "original" idea (creating a fake terrorist/owning terrorism) is wrapped up in so much generic, derivative crap that it cannot overcome. In other words, the twist is not worth the price that is paid via the bastardization of the character and the mythology.
You'll never convince most fans that this was the best way to go, because from a creative standpoint, it simply wasn't. Killian's version of The Mandarin was serviceable, and Guy Pearce did a solid job, but the character was largely forgettable. His motivations are thin, his character is cliché as hell, and calls to mind several less than stellar representations of classic superhero movie characters. We've seen it all done better, and several times over. This felt like a poor imitation of other supervillains.
Even Killian's powers are only marginally more impressive than his henchmen's abilities and skills. That's inexcusable in a main superhero baddie.
I could care less whether they try to hint at Kingsley being The Mandarin, because that would be a cheap move, wouldn't begin to undo the wasted potential.
As far as I'm concerned, "The Mandarin", much like Ivan Vanko, will be remembered as a big fart, and there'll always be the wasted potential there. And that's a huge disappointment. Imagine if The Joker had been given that type of treatment.