With http://www.gamesas.com/index.php?/topic/1184814-walled-cities/ I think this topic is now relevant again.
To summarize the thread: If a dragon attacks a major city in a seperate cell how does to game react when you exit the city (can you see the dragon?). I see trouble when it comes to dealing with dragons entering - exiting cells in terms of gameplay mechanics. Will dragons simply ignore major cities except for scripted events? If that is the case it svcks!

I hope it can be modded properly, yet I see trouble (if dragons ignore major cities): How will a dragon attack affect a major city where other NPC rules/routines and stuff may possibly apply (fx it could kill a stationary quest giver or something).

They've never said that the big cities are going to be attacked...

Actually, that makes sense, why would a single dragon attack a walled city with archers and ballistas on the wall? They have a better chance at smaller towns.

Well. At some stage they have to attack big cities eventually (if the hero doesn't succeed) I guess. I suppose it comes down to what motivates them: gold, fame, burn down the established culture/revenge, other. They also have dragon shouts which in theory should allow a powerfull dragon to make a suprise attack on a big city with some sort of succes.

In terms of gameplay I just find it discouraging that you can jump into this city cell and dragon is gone....

couldn't it be some kind of hybrid? like Markarth, part of the city may be on the side of the canyon (in the general world space) and part of it inside the canyon (akin to a huge dungeon/city)

This.

1. I wouldn't take for granted Dragons won't attack walled cities. It's a supposition. I'd say there are ways to circumvent the cell problem.

2. Actually i donot know what's the reason behind dragons attacking ciities. Wothout knowing thier motives I have no way of ruling out certain types of attacks.

Now that we know the cities are walled in, I think it's possible that they will have a system so that dragons attacking the city will appear far outside the playable region of the city cell, and when you leave, they will be transported to a corresponding location in the world cell.

He could have a point here to be honest,that could be the case. We have been told some dragons will be scripted.I believe that will be for story purposes. So as bukee said.Dragon attacks may be scripted in the larger cities as regards story,and the major cities would have alot of defence i would imagine. There are tons of other settlements,towns etc....those could be the one's that get attack randomly. There could be ways of doing it either way,which bethesda will have done already.

Oh for crying out loud! How do people think this is a problem?

Look, in a computer game a dragon is just a logical entity. It isn't solid, has no physical existence. You can have two, three, fifty simultaneous and identical instances of the same single dragon.

So, your character is outside a walled city. A dragon flies up and starts 'attacking' the city - which is to say the dragon flies up and starts breathing fire down on the empty area (which you can't see) inside the city walls. You run up to the gate and activate it. Your character is teleported to the city worldspace. Guess what? So is the dragon. Or a new copy of the dragon is created inside the city worldspace, only this version of the dragon has land-and-fight-on-foot AI code active. You and the city guards fight and kill the dragon. You walk up to the gate, activate it and get teleported to the wilderness worldspace. The game detects that the dragon was killed and deletes it from the game's data structures. Lo and behold, no dragon outside.

It works pretty much the same way if you're inside the city when the dragon attack starts - the dragon gets spawned in the city worldspace but beyond view. It flies over the walls into sight, lands and starts attacking stuff. Once you've got it's attention, if you leave the city while it's still alive it will be teleported out along with you so the fight can continue. Or a new copy gets created, or a variant that fights better outside, or whatever. If it was on the ground in the city worldspace, then when you leave it will be placed on the ground in the empty area behind the city walls, ready to take off and fly after you.

The point is there is no problem, just a bunch of coding and data handling - and, y'know, that sort of thing is rather what Bethesda are in the professional business of understanding.

In Oblivion, all characters had the ability to enter any cell (enemies would follow you through doors). So why is this any different with dragons?