I see they talk about the expansion relatively often, have they mentionned what their estimated plan for the expansion release was? Not a release date obviously not even a month but more like a general approximation, 6months, 1year, 1year and a half, that kind of thing.
Seeing a it's almost certain 2.6 is the last patch (Coil ends at 2.6) that would mean:
2.4: October
2.5: January
2.6: April
Expansion: Summer 2015.