There's no incentive that can convince people to stay and do things like roulettes on their home DC. Unless you make it extremely overpowered, but even then you'll have plenty of omnis that just don't care, while the amount of buffs you'd have to give would be on the extreme/game breaking side.

If you wanted to really do something then you'd have to go in the opposite direction and add consequences instead. Roulettes already give solid rewards, nerf the road to 80 buff off your main DC and whatever else. No one wants this though.

The real solution is just cross DC parties and queues. That's literally the only thing that's acceptable. And it needs to happen because it's not just Dynamis that's going to struggle. Eventually people are going to develop their own notions of which DCs within each region they think have good queue times, and which don't. It doesn't matter if it's accurate or not, but once that happens everyone will travel to the "quickest" DC in their region, leaving queues in other DCs struggling, even if that DC has a healthy population of people.