Hey there!
I've been lurking around this thread for the last week or so... and I've finally decided, that it's high time I let all of you know a VERY important thing:
You are amazing.
In all my years of being a lurker "extraordinaire" here on BSN, I've never had the pleasure of encountering a group of people so positive, kind and accepting.
Makes me all fuzzy inside to know that such a place exists.
The fact that this forum revolves around Cullen just makes it even better... 
So on that topic (of our dear templar, i mean)...ever since I've seen the new trailer, I can't seem to get rid of this tinny little problem (it's not really a spoiler, I just don't want to spam you with big pictures):
He reminds waaay to much of Alistair (albeit an older version of him), anyone else has this "problem"? Just me?
Oh well.....I guess I just needed to get it out of my system.
The wait for new pictures is killing me right now...ugh.
OK so... I'll... just go and lurk some more now.
Peace and cookies!
Sorry if my English is not up to par.. not really my first language...
Welcome! And don't go! Come, come, stay. Have a cookie!
Now, onto the pictures of Cullen and Alistair, because I love to analyze things needlessly in depth!! 
I think a main problem is that Alistair and Cullen already looked a little alike, especially when you look at the DA2 Cullen and DAO Alistiar pictures you posted. But, looking at the DAI Cullen image, you can see several things that read Cullen as opposed to Alistair.
1) His nose. Alistair has a bit of a hooked nose at the tip, while Cullen has a flat-bottomed nose. DAI!Cullen has this same nose.
2) His chin. DAI!Cullen's chin is slightly pointed. Alistair's chin is wider, and DA2 Cullen's has more of a point to it. Perhaps not as much as DAI!Cullen, but enough to see a resemblance.
3) His hair. DA2!Cullen's hair is lighter than Alistair's, and DAI!Cullen has very light hair. I'd bet Alistair's hair will be more red in DAI. Also, DAI!Cullen's hair is brushed backwards, similar to DA2!Cullen's. Alistair's hair is brushed forward.
Now, DAI!Cullen does have one thing that says Alistair, and that's his lips. Alistair's mouth is thinner, and DAI!Cullen's lips have a flattish look. And Cullen and Alistair share a very similar brow shape, but DAI!Cullen's looks more like DA2!Cullen's, to me. DAI!Cullen's jaw is shaded too much for me to get a good look, but it looks squarer than Alistair's.
Whew! There! 