There's alot of evidence pointing to brink having some open world elements to it. The fact that the Ark is an island is a clue with in itself.
how is this a 'hint' or 'clue' to open world elements?
The website has a lay out of the entire Ark which is broken up in sections. so far there are only two with descriptions.
Based on the factions page on the website, it looks like the Ark itself is split in half, with one side being dominated by security/Ark and the other being primarily Resistance territory. This most likely ties into the story and campaign. The descriptions of the different sections are probably just descriptions of different areas where you will play missions. (aka map descriptions) I don't think you will be wandering around the Ark, just choosing which missions to do - there is structure and order to the missions, this is why when you play the campaign, and you win a match, you stay to fight the next one in the story, whereas the losers need to connect to a different server and try the mission again - because they missions are tied together in a specific order.
and in one of richard hams interviews he spoke of having all the missions tie together.
yeah, UT3 tied missions together in a story also - not exactly a seamless, open world experience....I'm not saying Brink's campaign will be as dull and repetitive as UT3, but I don't think it's going to be something so epic to rival Oblivion or Mass Effect. Here is how I see it playing out -
At the beginning of the game, there will be a cutscene explaining the Ark and what has happened to the planet - to get players up to speed on things - then it will ask you "do you want to save the Ark" (security) or "escape the Ark" (resistance) you make your choice and start that side of the campaign. Each match has a bunch of objectives to complete, and by completing them, you advance to the next mission, which will have some cutscenes and story explanation, maybe move to anew section of the Ark, etc. then you start the next "mission" and and try to complete a new set of objectives, and rinse and repeat. Each mission is a map, just like with other FPS games, not some open world battlefield.
My guess is that you can move around the ark from section to section not an open world experience but close to it. each section holds different missions or send you to different sections of the ark.
each section of the Ark is probably just a map, or a group of maps - by "selecting" a section, you are probably just picking what map(s) you want to play. I don't think it's open world sections, like in an MMO.
I know they said something about having "collectibles" scattered around the map, in the form of intel, that you can find and return to a command post for like a team wide xp bonus.