User blog comment:Xilinoc/Ch. 547 - Peace from Shadows/@comment-1268838-20130904145545/@comment-5657895-20130904192134

No, Seireitei hasn't been destroyed, it's merely been switched with Shaten Berich, so Aizen should still be in Muken. Thank God.

Well they chose Seireitei I gather because it's the least expected place to hide and the Reishi is bountiful. In the Human World it's less so but not completely extinct, so they should be able to use it there as well.