based on the history of the previous 3 albums the next one will be written in winter/spring of next year, recorded late spring/early summer and released sometime in fall right before the touring season
Actualy someone posted an interview on this forum (http://www.puregrainaudio.com/videos/videos.htm), where he says that they will probably, after the touring this winter, take some time off and probably start work on the new next album in spring/summer or something like that, but that was all just speculation.