Does anyone know if FFG has plans to release more books for any of the Warhammer 40k, especially Deathwatch?

They're going to release an adventure book for DH2 sometime in the future.

Yeah there does seem to be a big slowdown in book production for some of the lines. But hopefully it just means we are getting a new edition at some point.

Probably for their SW system getting a beta recently and some splat books.