n?, every side has unique story, but the ending is the same for all. (last encounter vs Molog ball or what ever he is).

I'm sure there will be plenty of territorial capacity. After all Skyrim is only one territory. It's probably equal in volume to each of these three faction territories. On top of that, i'm sure there will be neutral zones and probably even instances which offer infinite resources and space.

there will be so many expansions that you can bet that there is some aspects of the game that is added at that point, what, we can only wait and see. one of them might be cross faction stuff.

Cyrodiil has lot more to offer then just pvp fights.
http://images.uesp.net/6/6c/ON-map-Tamriel.jpg ( tes online map)
http://images.uesp.net/e/e8/Cyrodiil_Map.jpg (Cyrodiil map from oblivion)

Even tho parts of the province wont be available at once (i'm just guessing since area from Anvil to Skingrad is grayed on tes online map,same as area south of Bravil), and some places are gone (im guessing most of inns and camps,some mines and smaller villages), you have an ample amount of forts,ruins,caves,and i guess some new smaller settlements or points of interest.

Typically in MMOs, you get different starting areas and questlines for each race, but at some point they converge.

However, yeah, if there are real choices to be made with real consequences, maybe you will still be able to have a semi-individual experience even after that point.

I would love to see class questlines throughout the game as well, though they'd have to make three versions for every class I guess :/

I've read that every race (from the same faction that is) starts at the same place of its faction territory.