Regarding Dinamo Zagreb being 2nd in the group, while being possible, i don't think that it will happen. They have good chance for being 3rd though and continuing in Europa league. That would also be a very good result.
But maybe i'm just too cautious as i got used to disappointments when it comes to Dinamo Zagreb and Euro games, i would say that this generation is even better than the one in the late 90s with Viduka, Prosinecki, Cvitanovic..
Why not Dinamo Zagreb can be second in the group? Obviously City is without a doubt the first place favorite, but Atalanta is joke team, they play worst football you can see in CL, and City is win over Shakhtar without any problems, as it is a light training, and not a CL game.
Dinamo can beat Shakhtar in home game, and take at least one point in away game, probably also play a draw in Bergamo. With 8 points second place is pretty realistic, but first they need to play with MC in Manchester, this will be good test for them.
I've been going to Dinamo Zagreb games since 1992, and more than once i had high hopes, but somehow they managed to mess it up each year, with 2 exceptions, in the late 90s and last year.
That being said, this Dinamo Zagreb really looks confident, more mature and a team with a plan. Dinamo always had very talented players, but this year they managed to keep all their best players except Sunjic who they sold way to cheap (imho he was 2nd or 3rd most important Dinamo player). I didn't say that they cant be 2nd, of course they can, but personally i think it would be very hard and for me 3rd spot would be good too. Atalanta played awful game and Dinamo was brilliant, but Dinamo can also play like crap, and i simply don't want to be caught in euphoria after only 1 round.
