The topic
The Road to Hoenn and beyond was created by us some months ago to answer this question and outline our planned roadmap. To save you time, Hoenn is planned to be the next phase once the Sevii Islands are completed. As for how long this will take, providing any sort of prediction right now is difficult, as there is much to be done before we can really continue with content.
As outlined in our
New Years Reflections and Roadmap thread, the current hold-up on Sevii are the lack of scripted NPCs. As PWO is undergoing a major overhaul of the scripting system, all NPCs will need to be rewritten; and the Content team have wisely decided to hold off adding new NPCs until the new scripting system is in place, so that we only have to immediately re-code them.
Once the new scripting system is in place and we have been able to complete and release Sevii, we will be able to focus on Hoenn. While I would be very happy for that to be some time this year, it simply isn't possible to provide an estimate at this time.