Nope that's not it in the slightest. Try this on for size.
Orks vs Guard Campaign
Team A (The Invaders)
Adam (Orks)
Bob (Orks)
Carl (Orks)
Team B (Imperium's Defense)
Dan (IG)
Elliot (IG)
Fred (SM)
Chaos Vs Imperium Campaign
Team A (Assaulters on a Chaos world)
Dan (Imperial Guard)
Geoff (Blood Angels)
Carl (Grey Knights)
Team B (Chaos Defenders + Merceneries)
Harry (Imperial Guard)
Josh (Chaos SM)
Kevin (Orks)
Some of the players stay on the same team (e.g. Carl), some players change teams (e.g. Dan), some players are brand new (e.g. Geoff), and sometimes even entire teams are changed (Harry, Josh, and Kevin).
The key is that each campaign is separate. There is no correlation between the OvIG and the CvI campaigns. There is no 'loyalty' between the two campaigns (so the people you play with in one are not necessarily the people you play with in another). Team A in one campaign are not necessarily the people in Team A in the next campaign.
But the more important things:
- Each player is signing up to a particular global team, as mentioned in the OP.
Nope. No global teams. Your teammates are your teammates for the duration of this two-month campaign and that's it.
- Players on a certain team will almost be like a permanent line-up when a campaign starts (Same players vs same players, no swapping teams)
Nope. Your team line up can, and almost certainly will, change between different campaigns.
- Team A and Team B are assigned "Roles" in the campaign, after which participating players nominate their army (and why/how it's in the campaign, eg. the Blood Axes in the Chaos Campaign)
Potentially. At this point I'm not suggesting which way we do this, either picking campaign roles then assigning armies or picking armies first and those players, or an associated GM, choosing the basic plot to which roles are attached. I'd prefer the latter, if I'm being honest.
- Campaign Plays out for 2/3 months
- Campaign sums up, new campaign starts
Yep.
- So in a way, the team's shouldn't be called Imperium vs Evil, or anything. Just 2 team names and people sign up for them. Because you stick with a team, but could be playing for the Imperium one campaign and for Chaos the next.
Nope. You're still thinking of the whole "sign up for a global team". That's not what I'm proposing. Each team in any given campaign may well have their own names. Let's take the two examples above. For the first, Orks vs. IG campaign, the Orks could be "BadDakka's Waaargh" and the Guard could be "The Defence of Straggler's Hope". For the second, the Imperials could be "The Emperor's Fist" and the Chaos side could be "The Forsaken".
Does that also mean that how we split Eldar/Tau is now irrelevant - we just sign up to a team then sort out the chicken business when the first "campaign event" starts?
Essentially, yes.
My perfect situation would be for each campaign to have a limited focus, with a GM deciding the basic plot (such as an Ork Waaargh invading an Imperial Agri-World or the Imperium attempting to reconquer a renegade Forge World) and assigning particular army books to each side of the conflict, then having players sign up to either side to do battle and so forth, with a conclusion within 2 months so that a new campaign can spring forward, presumably with a different GM.
That is, in essence, what I am proposing. But I am in no way suggesting that that is how it should be done. It's only a proposal.