Coupled with the ending images of the kids, that says dream state to me. If you want to believe he's back in reality, that's fine with me.
You must have posted this while I was typing my last post. By sheer coincidence I just found this a few minutes ago:http://www.cinemablend.com/new/The-Mystery-Of-Inception-s-Ending-Solved-19931.html
The potentially significant part is that the costume designer claims the children's clothes are different in the final scene. I have to admit, they looked the same to me, and apparently to the guy who wrote that article. Next time I watch it I'll have to make a point of looking for some difference.
On a side note, does anyone else smell BS with that Nolan quote above? Seriously, did this guy get coached or what & does anyone find the "emotional significance" disturbing? He's basically saying that reality and truth are unimportant. The only important thing is how you feel. The kids don't matter, everyone else in his life doesn't matter, his sanity doesn't matter. Being insane is fine, just so long as you're happy. Great message Nolan. Light up another one.
I hope it is BS. I'd rather it be proven to be a dream than that "it's impossible to tell" crap be intentionally the case. If that's the case, there's no point in even thinking about it, because there's no answer to deduce. Heck, I might as well just make up my own ending where Cobb was actually only dreaming that he was a wanted fugitive with a technology that allowed him to enter dreams, and we just didn't have any way to know it.
And yeah, so the real point of that scene was to show that Cobb doesn't even care whether he's dreaming, insane or whatever the hell, and screw everyone else, including his kids and Saito (That is, if he is, in fact, still dreaming, which Nolan claims is impossible to know).... God dammit, I hate intentionally ambiguous endings (except for Pan's Labyrinth, but that's only because I wanted to believe Ofelia might have really gone on to be a fairy princess after her death.)
Sorry, it's 2am here, I haven't slept since Thursday, and I'm both crabby and more than a little bit out of it.