How would this work?

Not so sure that this would even be possible, unless you are talking guild alliances.  Certainly would not be able to form an alliance with Daggerfall or the Aldermeri in Cyrodiil.  Besides the concept of 2 alliances against the other other one reminds me of Blackgate and Jade Quarry against SOR.  No pleasant memories there.

In 3 faction warfare you are and always will be against 2 opponents. It's the very reason they have it this way. In 2 realm games one side typically grows larger than the other and the balance turns the tide which then thins the population of the other faction. In 3 realm games the little dogs can gang up on the big dog. 

The Problem with Guild Wars 2 is that it's Ranked. For a server to keep 2nd place they need to beat down 3rd place. There is no benifit to them working with 3rd place to take down #1. If they risk it they could risk 3rd taking 2nd or first from them. This is reversed from the way DAOC and ESO are structured. In DAOC  and ESO the guys getting beat down tend to work together to take down the bigger guy as they hold the relics and it takes the full power of both of them to overcome the stronger foe. It's tactics and diplomicy.

That said. ESO presents a new element in the form of Campaigns. You can switch campaigns at any time. If you are finding 2 opposing realms are beating you down just because they want to be mean you can switch home campaigns to a different one where you feel a more level playing field. You can also guest in other campaigns. There will be dozens of Campaigns open at any time.

I'm glad to hear that!  My fear was that we would be back to the days where in DAoC the Mids and Albs would team up, decide what keeps they wanted for which realm and for the most part.....control all of pvp that way.  We'll see how well they manage the 3 realm campaign.  I'm still not sold that they've handled the 2 vs 1 thing and can't be until I get to experience it 1st hand.  Just my 2 coppers 

so game is phased like Aion basicly to many people in your area  , you can bring up phase window and choose  between another 10  instances of the same world ? 

More automatic than aions. The server tries to pair you, your friends list, and your guilds in the same instances. You do have the option to travel to groupmate which should put you on your groupmates instance.

 I understand that the game is still in the early stages and we don't have all the information. So I keep holding out for more official information from TESO creators that will lessen my concerns.  My main concern is due to the fact that you can play all three factions on the same server. ( I am assuming this from what information I have read thus far.)  I have a few reasons why this concerns me. The first problem I see is that instead of the two less powerful factions teaming up, people instead are going to switch characters to the most powerful faction of the time.  Thus instead of working as a balancing mechanism it ends up becoming an unbalancing mechanism. If you had to go to another server to play on a different faction then I wouldn't be at all concerned but I haven't read any thing thus far that states that.  My second concern is faction spying. Basically some one logs on to a character that is on an opposing faction, then follows the armies around giving out the troop movements via Raidcall, vent ect ect.  Again if you have to go to another server to play a different faction then my concerns are mute. However I have thus far not heard any thing hinting towards that. 

 Again, I understand it is really too early to get too worried. Maybe they have some other ideas on how to address my concerns. Who knows. Just have to wait and see. 

Clarifying something.. the Cyrodiil map will have "campaigns". Which you can think of like a war. You cannot have different faction characters fighting the same "war". So our Ebonheart toons can't fight in the same "war" as our Daggerfall. Meaning.. we won't be fighting Gaiscioch if we're on different alliances.. Not sure if that's clear enough. but that's what I understand from the way Cyrodill wil work.

 So if I understand you Jedgar, the Ebonheart faction that is on our server wont be fighting the Daggerfall  that on our server? It will be a Daggerfall from say another server type thing?

There is only going to be one mega-server in ESO, but it will have instances. When in Cyrodil you "sign up" for a specific campaign (Campaign A, Ebonheart Pact) that lasts for a period of time (a month if I remember correctly) that is faction locked for you. If you have characters in a different faction (Aldmeri Dominion) you cannot sign up for Campaign A or C with them but Campaign B, then Daggerfall Covenant characters could be in Campaign C but not Campaign A or B. We'll just need to know which campaigns we're in for each faction.

 Oh I get it now. Well that sounds pretty cool then.  Pretty much mutes all my concerns.  Now I understand how this alliance works. If we're in campaign A with Ebonheart and we as well as Daggerfall are losing to the other faction we can form an alliance with Daggerfall in campaign A.  See? I knew it was too early for me to get too worried. Just needed some more information. Thanks guys. 

We will declare 3 campaigns one for each realm after the first week the game goes live. We want to make sure to choose an empty one for ebonheart and medium ones for yhe other 2 realms. We want to avoid the ones that are full as I dont want you guys waiting around in queues to get in. 733 people per campaign per faction as of last public estimate. We will target the low pop for our primary group.

How does a campaign work?  I understand timed PvP instances, but I'm a little fuzzy on campaigns.  If we take a keep, do we have to be ready at all times if someone wants to take the keep from us?

Each campaign is like an open all day and all night zone for the duration of the campaign.  Just like in GW2 anyone can come along any time and attack anything they want.

Okay, that helps a bit.  I've never played GW or WoW and a little under-schooled in the particulars of large-scale warfare.

It sounds a bit intense.

Ezasme, the campaigns are very helpful in figuring out who is Emperor. At the end of the campaign (which I have heard will be timed to 3 months), all Alliance points reset. You keep all property your guild/alliance captured, but points for having killed other players and so on will be reset, which means everyone starts even again on the leader board. The leaderboards are per campaign (not just in time, but also in phase) so you are compared to others you play against for not just a battle, but a mini war. The player at the top of the leaderboard for the alliance that owns all six keeps surrounding the Imperial city becomes the Emperor.

And as Emperor you get a special skill set to lvl up/use.