Claims that botnets would be a threat make no sense to me, why would we mind few botnets even with 100K machines under them if we have 100M machines successfully mining coins? Botnets can not have double digit percentage of machines polluted, they would be detected since it's obvious they are working in the background, so let them mine their few percentage of mining power.
I've written similarly, but note that getting to 100M takes time and perhaps much of the supply is mined before you get there, especially with coins that have diminishing % rate of debasement (i.e. most all of them).
Problem is that it's very difficult to find the hashing algorithm that would be really ASIC resistant, not to mention GPU.
GPU can be defeated because it doesn't have specialized instructions and the CPU does, but preventing ASICs is impossible (if the incentive is large enough).
I had thought of both of the ideas mentioned in the
"ASIC Resistance" section. Neither will defeat ASICs. And I see that Vitalik hasn't seen my analysis of Cuckoo hash, because I argued it can also defeated with an ASIC.
Instead I think the best goal is the algorithm should be one that it is likely to be highly needed for general computing and thus Intel will continue to accelerate it and motherboard vendors might even build on an ASIC to each motherboard. Bitcoin USB ASICs with the similar power efficiency of the bigger models now cost only $15 at Amazon.com.