I would think so. It has the classic anvil structure, has capped out, and has begun building again pushing up through the original column. It still has convective energy, and while it's hard to say what the precip output at the bottom might be, it has the markings of a cumulonimbus cloud. Remember that a Cb doesn't need to be outputting rain to qualify, and the building stages of a Cb are characterized largely by updrafts.