Considering that the one area we've seen anything more than a few seconds of contains the city of Redcliffe (midsized for a medieval city and occupied though it may be) and more land footage than DA:O had in the whole game... I think it is more than reasonable that the at least one of the three+ other regions we haven't seen could have more than enough room for a city much larger than several Kirkwalls and still have room for open ground exploration, where you could be at one end of the map and not even see the massive city on the other side till you start walking that way. You have to get out of the load screen mindset, Denerim was small - four areas each about the size of Lothering, so if that's what we are calling a big city then they could fit half a dozen of them in the area they've already showed with room to spare. They've said there are at least, what, four regions; each larger than the whole of DA:O and 2 put together and once you load an area you wont have a load screen in that area, meaning that Val Royeaux could be the center piece of a large map that has many small towns and villages around it and still have room to spare if they are even being remotely honest about the size of the regions in this game.
If you think Redcliffe is midsized for a medieval city, then I suggest some additional reading. Other than that, it seemed comparable to Whiterun, which was also the size of a modest village, although it looked more 'urban' because of the way it was laid out.
I'm guessing we are going to have a few villages, an encampment or two and several keeps with traders and artisans.
It's not going to look good compared with Witcher's Novigrad or AC's Paris, but we were never going to get that anyway. Cities are not Bioware's forte and I guess they have, erm, sidestepped the problem.