The problem is... how do you recognize "evil" blocks? What properties do they have that make them unique from other blocks?
If such a system was in place, a list maintainer (or some other entity) could issue something to build into the block as an identifier of origin. That's just the first idea which came to mind and there are probably other ways to do it (if network analysis by the list maintainers were not sufficient for the task.)
list maintainer= central point of failure/control/attack
Let me say again, ASIC is inevitable. That is not the problem. The problem is that it is too soon.
Right now it is doomed to failure for the INVESTORS. The price of bitcoin is just too low and the ASIC miner (in the hands of one entity) will undermine confidence in bitcoin and make the price even lower. The investors will not get their money back and bitcoin will be damaged. ASIC mining will make sense when the market cap of bitcoin is greater and it would be harder for one ASIC miner to control 50%.
The odds of a single entity going to a reasonable share of mining without surpassing it are quite low. At 20% the network will exist just as it does today, but once you pass 40% confidence will start to erode and you will be acting as a 'tax' on bitcoin by driving so many of time mined coins to be exchanged for fiat.