Well - for all we know he could be swimming in a pond in the UK right now <g> but I am expecting him to show up in one of Rich's next Doctor stories. Perhaps this one - the brain in a dalek suit vs vampire? Or perhaps not till a later one, with the Master in it. I'd love to see the three way tango between Masters Doctors and Dalek Ahn, as none of them can trust the others.
For me, there's that much more to look forward to in the next story. See, Rich didnt make the mistake of killing off all
the interesting bad guys, and then having to recreate them all over again to use them in another story.
Not that I'm pointing fingers or anything
....just leaving signs RTD
vs genocides of Daleks