WIS gave away a lot of free teams. Some of those owners will stick with their free teams and purchase more seasons--many wont.
They made no money off of the initial promo. With the new world, they will get the mix of veteran coaches and new users who were maybe on the fence for a new team, or who are really hooked and want in from season 1 on a supposedly level playing field.
They will also be giving a way a lot more free teams, it would seem. If they are notifying new users via e-mail of the new world like they have done in the past.
If they keep this promo going for awhile, D3 will stay relatively full across the board. And they will make their money on the percentage of users that keep renewing.