I don't get the fascination with the single tier stand or single "second tier" at North Stand people are going on about, think people see Dortmund's atmosphere in their end and get carried away. It isn't the shape of the stand or if on one, two, or three tiers, it's who is in them that creates the atmosphere.
The North Stand is currently a family stand, if you want to create this huge single tier stand you are going to have to move the family stand or it is wasted, but where to? South Stand, which currently has the best atmosphere and away fans? They aint going to put kids next to away fans. They also aint going to stick them on the third tier somewhere, we want to appeal to new generation of fans as much as poss as we have(had) such an aging average age of fans so they aint going to stick them in the gods.
Only real option is to have them in North Stand lower, below the second huge tier, but then the whole point of it in the first place is the atmosphere, so again not really seeing the benefits
I think safe standing would change things, I grew up watching City (born '82) on the old standing Kippax, sitting on the barriers as a kid, getting pushed off when we score and then trying to rush back on quick before other kids took your spot, so totally "get" what people want regards atmosphere, and if there was a standing end I would want to be in it, I just can't see it anytime soon, and without standing and moving of the family stand, I don't really see the benefits.
That said, I have to pinch myself sometimes with where we are nowadays, the Etihad is just amazing as jrb above photo shows, and will get even better, and whatever they decide for the NS I'm sure it will make it an even more impressive stadium.