What is happening with ASICs currently has happened before, but in a different way. When CPU mining changed to GPU mining, those still mining on CPUs were getting smaller slices of the pie, but had the option at the time to go out and purchase at least reasonably available hardware to compete with others making the same change. Something similar happened with FPGUs, but at a smaller scale because of the relative cost of FPGAs, the only major gain was in the reduced power utilization in most cases, and the looming of ASICs not long afterwards.
The key difference is that you could make your own miner on a CPU, on a GPU and even on a FPGA (I recently made a miner with 4 Artix-7 FPGAs mining at 1.6 GH/s for $650). But you can't make yourself an ASIC miner, that costs too much. So you can only beg companies like Avalon or BFL to sell you some. But it will be more profitable for them to mine on their own than to sell chips/devices to you (constant, controlled income vs one shot). What if they stop selling miners and mine on their own? We'll have to shut down our miners after some time and whole mining will be controlled by 3-4 ASIC companies. That's the end of mining.
I gave up my FPGA project - even if it's cheaper than ASICminer - because at current difficulty (and difficulty increase rate) the ROI rised to 6-8 or even more months. I have better investments than that :/ I'll leave these two PCBs I already made running and forget the whole thing.
P.