Well, if we are going to go around turning puppies into sacrificial offerings and burning down every orphanage we come across and just being a complete asshat in general while letting Thedas burn to the ground, then I don't expect him to like our quizzys 's at all. With the betrayel thing though, its a hard one to call since it has been said that the adviser's don't leave the Inquisition when they have had enough of your crap like the companions do. It will be interesting see what happens when November gets here, though I don't plan on playing a jerk so I doubt Cullen wouldn't be loyal to my Quizzy's. I think we are safe as long as we do what is best for Thedas. 
An OT question, but I was thinking about how it was said that we could wind up at the end of the game (if we try extremely hard) with only one companion remaining. At first I thought that it would be someone extremely loyal to the Inquisition like Cass but today it entered my mind that it could be Cole. If he is as child-like as I'm gathering then maybe he can be convinced that everything the very naughty Inquisitor is doing is for the "greater good". Who does everyone else think could be a possible last remaining companion if everyone got sick of your douche bag ways.
I don't think it would be Cole, just because it's been mentioned that we can bypass him entirely. If we wanted to try and figure out which of the 9 would be the one to stick with us despite all of our uh. Bad decisions (an understatement, I'm sure), I think we should figure out who our "core" is. Like, I'm sure that there should be at least 3 companions that we pick up in the critical path of the game and therefore can't accidentally miss, right? (Turning or chasing them away is a different matter here.) And it would make sense if it was one companion of each class.
I'm drawing on hazy memories of ME1 on this assumption about the "core" group here, because if I recall correctly, the game is structured so that even if you turn away some squadmates, you're always left with at least one tech, one biotic, and one soldier (Virmire nonwithstanding), which is Tali, Liara and Kaidan and/or Ashley. You cannot go along the critical path of the game without them-- Liara is found on Therum, you can only kill one of the VS's and can't get rid of the other one in any other way, and I think Udina or Anderson or someone insists on you taking Tali with you anyway, even if you say no.
So I'm putting my money on Cassandra and Varric, because that's our warrior and rogue, respectively. Cassandra, because she's kinda obvious, what with the whole holding a blade up to our throats and "The only danger I see here is you", and Varric, just because last we saw, he was with Cassandra. It can't be Cole, because they've mentioned that we can bypass and/or turn him away entirely (for those players who are all like, "Rah! Demons! Hell no!"), which only leaves Sera. Of course, that also doesn't put her out of the running.
So the only slot we'd be unsure of is our "core" mage. In this case... I'm actually going to put my money on Solas over Vivienne and Dorian. Vivienne invites us to a ball, but there's a chance that this might not be a part of the critical path, right? It could be a quest that we can ignore completely (although why you would I dunno, because an Orlesian ball sounds fabulous), or it could be something that never happens at all because she only extends her invitation if you gain enough importance and influence (a possibility I've seen thrown around the forums a few times). And Dorian... well. I dunno. I'm going with my gut here. :S
As for why I think Solas would be our "core" mage, well, it's a game that has a large part of it predicated on our PC's trying to fix the great big Fade breach in the sky spitting out demons and spirits and the like, and we're the only ones who are actively doing anything to fix that. I think Solas comes to us, and whether your Inquisitor agrees with his ideology or no, doubtless there's going to be someone (Cassandra? Your advisors?) who would object to you turning him away and not making use of his unique expertise. In which case, I mean that if you, the Inquisitor, won't allow him to join and help, one of your advisors or Cassandra will step in and take him in in any case.
Well. All that, and Solas sounds like "Solus", as in Mordin Solus, who was also written by Patrick Weekes, and you can't get through ME2 without Mordin.
Am I projecting some unresolved Mordin-death issues here? Probably. 
As for who our "one" companion left at the end might be... hmm. My money is on Cassandra. Although, I do have a tiny theory that maybe all of your companions can die depending on your decisions, but the game has been designed so that you'd always be left with at least one no matter what. Which renders all of my blathering about having a "core" of three moot. 