2 points:
1- as we get more expansions and patches, new people will arrive in Dynamis. And they will make it with 8 servers at some point in future. So, as the population grows, like you said, around 27% will continue to travel and do stuff in another DC, but 73% will stay on Dynamis, making it grow as the population grows. We just need to have patience. In the beginning, all servers and DCs suffered the same. So, it's normal to struggle in a new DC like this in it's first year.
2- someday, the DC travel will be available for different regions. So, maybe all the queues will be cross-region as well. In this way, no matter how much new DCs they make in the world, "everyone" will queue with more people.
So, in general, just wait for it. like Yoshida loves to say: "just look forward to it" and "we appologise for any inconvenience this may cause" also, "return to the Waking Sands at your earlier convenience" '-'