I really don't think the halving block reward in December will be very disruptive.
To someone holding bitcoins, that is correct.
To a mining operator whose margins are marginal (e.g., paying average or above-average electric rates and mining using GPUs) or even mining profitably at these levels, the block halving will be brutal to GPU mining. Like ... come block 210,000 it will be exit stage left, NAO!
Incidentally, by late fall FPGAs will probably already have pushed those GPU mining to make plans to shut down GPUs at block 210,000. If the ASICs start shipping before then, the date for exiting simply gets pulled forward a matter of weeks is all.