I don't see how anyone is thinking the release of ASICs is in any way going to centralize Bitcoin mining.
For example, I personally could already be mining, but the reason I haven't done it isn't hardware cost. A cheap graphics card isn't exactly extravagant. It's because of (1) the hassle (mainly heat output, but also other problems if scaling up) and (2) the electrical costs. That's just not convenient for casual mining.
Now, I can pre-order a $150 device that draws less power than a fluorescent light bulb and has nearly-negligible hassle, and keep it turned on for the heck of it. I'm helping secure the network, and making a little in the process... it's about like CPU mining before the GPU days, but with a small(ish) upfront cost. And the fact that I have pre-ordered one, but had no intention of GPU (or FPGA) mining just proves that the market of potential miners has expanded, not contracted.
Seriously, I don't understand the fuss.
(Even the 51% attack is less feasible... with more people mining, and a higher hash rate per miner, it's win/win. And it's not as if some agency couldn't just make their own ASICs if no one else did, although eventually someone was bound to.)