The Black Templar are missing now from the GW website. You can see it here,
http://www.games-workshop.com/gws/catalog/armySubUnitCats.jsp?catId=cat1400013&rootCatGameStyle=wh40k
Yesterday they were missing, but this seems to be fixed now. So perhaps it was just a site problem.
Does this mean that the Black Templar are getting rolled into a Space Marine codex? At the moment we really do not know. Although there has been a rumor of a Space Marine launch in June, it is expected that Eldar are next, with a marine codex later in the year.
All we know at the moment is that the Black Templar are missing, with an unkown future.