I wouldn't say deflation is killing bitcoin.
What it's doing is making people put off what they don't need to buy today. Yes, this will cost some businesses some of their profits for a while. But that will stop after the depreciation tapers off.
Granted, we're talking about MacroEcon, so there are always going to be exceptions. Just how many exceptions, I can't tell you because I haven't really seen any solid data on the subject. There isn't a BLS for bitcoin that I've seen.
Personally, I'm not spending right now anyway because I'm saving up for a second GPU to drop in my machine.