For it to make sense to move the EU marked worlds to an EU specific datacenter, it has to be cost-effective as well.
To make it cost-effective, you need time to plan and prepare.

I believe I saw in some JP thread a discussion about something that would require a datacenter expansion, and the time estimate mentioned then for that work to be done was 6 months, and that's just for an expansion (since it seems their datacenter is already cramped).

They could be planning to move the EU worlds eventually, but I really wouldn't expect them to announce it until earliest some weeks before an actual move.

An actual move would need to be announced in a timeframe like that, and possibly allow for free transfer from EU world to NA world for people that want to stay on NA datacenter, as well as the other way around...

Realistically, it would also coincide with a major patch... If it's going to happen any time soon, I'd expect it to be done for 2.3.