Thanks for the input, guys. I thought maybe they were phasing them out for the PPQ.
Walther has made it clear that they have no intentions of discontinuing the P99AS model anytime in the foreseeable future. The P99QA model was discontinued with the introduction of the PPQ (which is just the US-market version of the P99RAD/P99Q, which has been on sale in Europe for a number of years).
Walther tends to ship to the US in large batches. P99s were plentiful in late 2010, and again in late 2011/early 2012. My guess is that they will start to show up in decent numbers again soon. There is usually a full-size P99AS on display at my favorite local gun store, but I haven't seen any compact P99c AS pistols lately.