When they've suspended the demo timer in the past, they've waited 4-6 months before turning it back on (about 4 months following the 2017 hurricanes in Gulf of Mexico, 6 months following the flooding in Japan last year). In both cases they gave players a couple of weeks advance notice on Lodestone and it coincided with the release of a patch.

I'm expecting it to happen this time with patch 4.56, which would be 5 months since it was suspended at the end of October. That way there should be housing from demolitions becoming available about the same time they do the data center reorganization with free world transfers. It's still a guess on my part, though. SE won't say anything until they've got a firm date set for it.