An alternative way of saying that Bitcoin is deflating is that the purchasing power of Bitcoins is growing. Recognizing that the purchasing power of any currency is driven by two long-run factors -- changes in productivity and in the money supply (and money demand) -- BTC will have a natural mean (trend) in terms of a basket of goods. The question is whether, in this initial adoption / speculation phase, we are above or below that mean trend.

So while you might technically describe it as deflation, it might simply be reversion to the mean, in which BTC becomes more valuable until it reaches a saturation point.