Dominion is a weird expansion compared to previous ones.
For one things, the majority of ships and modules and the mechanics that govern them are not changing. Sure, projectiles are getting some love and Minmatar focused pilots are thrilled about that, but everything else is pretty much business as usual.
Faction ships are getting overhauled, but they make up a small percentage of the ships in space. Capital ships are getting overhauled, but for the majority of the playerbase that is not going to affect them, and even amoung Capital pilots only those rare few with Titans and Motherships will be greatly impacted.
If that is all there was to Dominion, I'b be tempted to call it a content patch instead of expansion. But its not.
Sovereignty. Its the basis of the endgame for Eve as much as it has one. Large groups of players working towards a single goal of taking and defending their own space. That it is due for an overhaul is not questioned. The real question is how is it all going to shake out?
We can guess what the developers want to happen. They want more Providences, that is to say, they want more pilots per system such as you find in Providence. CVA's unique NRDS policy (and working hand in hand with the Holder alliances like Paxton Federation) may be a bookkeeping nightmare when neutrals wander into the region, but it has allowed a larger population than you would find in normal NBSI space. Couple that with the agressive station building and the "crappy" region of Providence is one of the most dynamic and active regions in null sec space outside of NPC space like Curse or Syndicate. Development is the key to CCP's vision; they want alliances to invest in the space they occupy.
The upshot is that in order for an alliance to populate and development an entire region, you need a hell of a lot of active pilots. So there is either two end results if you want to maintain control of a whole region: you either have a lot of pilots working the new mechanics to develop the majority of the systems; or you charge of lot of isk per pilot to pay the fees to own the empty undeveloped systems.
Faced with two hard choices (bloat or bankrupcy) I expect very large space holding alliances to contract. A lot. If a properly developed system can support 20-50 active pilots' money-making enterprises, that would replace an entire constellation of pre-Dominion systems. Its feasible that a 1000 pilot alliance could live comfortably in a single constellation.
So let's say most large alliances do shrink from region spanning empires to one or two constellations that they develop agressively. What happens to the space they vacate? Well, they don't want just anyone moving in next door so there would be negoiations, truces, and alliances of alliances so that a pre-Dominion single colour region map becomes a patchwork of colours working together... much like CVA and the holders in providence.
The upshot of this is that you have the ability to fit a lot more friendly pilots into a region and gives you a larger pool for calls to action, but faced with communication hazards a single alliance would not face like which comms to use, who is the FC, where to rally, etc.
On top of all this space contraction and local development, the new mechanics means it will be harder for alliances to engage in campaigns far from home for long periods of time. In order to develop systems alliances will need ratters, miners, explores, builders, etc and combat pilots to defend them. Combine that with Moo Goo getting nerfed, alliances will definitely need these carebears to generate income to pay for the control of their space.
I expect some alliances will become nomadic rather than become slaves to carebears. Maybe even become hired guns for alliances that hold space and make money but lack the interest in intense PvP. Will Mercenaries become sexy again?
All in all, Dominion is going to change the game for the entire player base. Even high sec dwellers will feel the impact as null sec space becomes more populated (or more empty if Dominion is a failure). December first is coming, brace for impact.
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As a side note, I was so looking forward to the Dec 1st scramble of alliances in the new sov regime. So I was quite disappointed to hear that there will be a grace period overlapping the sov systems to allow alliances to maintain their cyno beacons, jammers, etc while the new system takes effect. I've heard the grace period will be indeterminiate amount of time and I've heard 35 days (5 weeks).
While I understand the reason the developers will be doing this as to not piss off existing loyal customers in the existing space holding alliances, I will miss the chaos that was promised from a sudden switch on Dec 1.