How ? Cole was listed among the "Characters scenarios" unlike Cullen.
What points to Cullen being a companion ? Apart from a picture in the survey and his presence in the War room concept ?
No, please...no.
Well, we have seen actual concept art of Cullen, and none of Cole. Not that there are screenshots of either of them, UNLESS that one screenshot with the party vs. a troll actually has Cole as the guy in green. I would think if he were a planned party member, and had not been scrapped, we would see some representation of him somewhere. The alternative would be if he is intentionally being left out, and was considered so integral to the game and its plot that he was the only character who was never on the chopping block. Somehow I can't buy into that theory. Our only hint that he may exist in the game is actually the "deceptive wax fruit" description, unattached to any character, that the devs tweeted.
As for locked-in/locked-out companions... I'm not against that as long as it makes sense. But I do not believe that is the case, in DA:I. For instance, I'd be fine with it if I'm choosing between apostates and templars. Obviously one group is going to have to die, or else I'll just lose their loyalty. Might be that if I pick Solas, I can't have Cullen (assuming he exists in-game), for instance. It would not make sense for certain characters to be willing to work together, and it would make for a game that is more replayable. What I don't agree with is a situation like the start of DA2 where one sibling dies depending on which class we chose for our character. While it did affect party balance, the only plot reason it happened was to provide angst for Hawke. But, if I'm having to choose between an apostate and a templar, that decision has weight and meaning to the plot.
For DA:I though, I think there are nine total companions. It is entirely possible we might lock out one or more of those companions depending how we play. I don't think Bioware is going to turn around and say, "Surprise! There are actually 10/11 companions, you just get to keep a total of nine!"