The survey was sent out by EA themselves, which suggests cities as much as twice the size as the current grid (which is smaller than a conservative plant pot.)
You can find the survey here, but here’s a screenshot of some of the information found on it:
All the features are listed as “potential”, suggesting user input could drive some major changes to the game, which is entering quite considerably into the post-launch support stage of the games’ release. Major content patches and fixes have already been released, but no major roll-backs on design decisions have been made or announced yet.
The offline mode is suggested via “Classic Mode”, which suggests that users could at some stage play offline or online, according to the sheet. However, there is no more information about this.