I personally am still pro-ASIC mining for various reasons. Mainly because it increases the stakes that miners have in Bitcoin; to a lesser extend because it decreases the vulnerability of Bitcoin's PoW to future quantum computers (under the premise that early quantum computers will be even more centralized than early ASIC miners).
I don't follow how ASIC or gpu based PoW would have anything to do with QC vulnerability. Actually I believe they don't.
I assume you are speaking of SHA256 immunity to QC attack but it is the same for ProgPoW and many other gpu/cpu friendly algorithms, they are as resistant to QC as sha2 if not even more. QC is supposed to crack ECDSA encryption in the transient phase in which pub key is disclosed by user (to claim the utxo) and has nothing to do with mining.
ECDSA is definitely the more worrisome factor, but I'm indeed referring to using quantum computers for mining.
While quantum computers don't have any apparent computational advantage over classical CPUs as far as SHA256 is concerned, they are also not especially disadvantaged. With classical computing reaching its physical limits and quantum computing just getting started, it seems rather likely to me that quantum computing (assuming it doesn't hit a wall itself) will outperform classical CPUs / GPUs in terms of SHA256 hashes within our lifetime -- with ASICs offering a much wider margin of safety.
I have to admit though that this point becomes utterly moot under the assumption that Bitcoin's future PoW scheme is as resistant against QC as it is against ASICs.
Given the size of the industry nowadays I also have my doubts that a mere switch to GPU / CPU mining would help decentralization all that much; at least not without additional measures to make pool mining significantly less attractive.
You are absolutely right, and you may be already aware of my other proposal, Proof of Contributive Work, PoCW which is presented in a topic titled as
Getting rid of pools ...Obviously, we are discussing a hard fork here and it is totally possible to have both at the same time but we need to discuss each issue separately. I'm afraid getting into pooling problem would be a distraction here.
I'm aware of your proposal and didn't mean to distract
I just think it's worth keeping in mind that not ASICs per se are the problem, but the centralization that they enable (ie. nothing is gained if we get rid of ASICs only to be re-centralized soon after).
Regardless of this, economics of scale would still apply and whether big miners buy ASICs or GPUs wholesale seems to make little difference to me. However I'm not quite up-to-date with the current mining hardware market and Bitmain's stranglehold may be worse than I think.
It would be interesting to see what sharing mining hardware with Bitcoin would mean for alts though (and vice versa).
GPU industry is far more competitive and healthy than its ASIC counterpart and more importantly, gpus are distributed around the globe more evenly. A gpu friendly algorithm of any type has a large memory footprint (to resist being cracked by ASICs like what happened to bitcoin) and memory banks are a rare resource with limited global supply, a scene that is unlikely to change for near future.
IMO, there is nothing to worry about gpus being monopolized, nobody could afford such a huge investment because the demand for mining is a fraction of the total demand for gpus and manufacturers won't sacrifice their market for a tricky one time business.
Is it though? The GPU industry is essentially a duopoly of NVIDIA and AMD, with Bitcoin's GPU mining era having been an AMD monoculture. Additionally the 2017 bubble had enough of an impact on the GPU market that regular gamers were facing a supply shortage and prices inflated way beyond the original release date prices. And that was just alt coin mining, even excluding Scrypt-based coins.
GPUs are definitely wider distributed than ASICs, but don't underestimate the market impact of crypto. Given a crazy enough market high-end GPUs (ie. the ones that are relevant for mining) can become just as hard to attain for the common mortal as ASIC miners.
As of altcoin gpu miners, I believe it is really interesting because they can act as another stabilizing factor.
Funny, I personally assume quite the opposite as I'm instantly reminded of the BCH / BTC hashrate fluctuations and the recent 51% attacks on minor alt coins. Not necessarily a problem for Bitcoin, but definitely not stabilizing for the ecosystem as a whole.
That's just my thoughts though, what leads you to the conclusion that Bitcoin sharing hashrate with alts would be stabilizing?
In cryptocurrency we have no assumption about loyalty, all in all it is about being rational instead of loyal. I know you are aware of this point I just don't get it why should you make such a weird argument tho.
If your investment is at stake and you can't use it for anything else (as is the case with ASICs), loyalty becomes the rational choice. Granted, it's the kind of "loyalty" that only lasts until the hardware becomes obsolete, but that's still a couple of months of hashing that you would otherwise need to continuously compete for.
Let's forget about 50%+1 attack, not everything is about such an attack and it will never happen for a big fish like bitcoin or ethereum and smaller ones should take care of their business by smart measures, I've proposed one earlier: require more confirmations for more precious txns.
Requiring more confirmations is the obvious solution, but also an incredibly impractical one. Having your customers wait for a day worth of confirmations on the off-chance that a someone is about to mount a 51% attack is rather crippling, even if you only apply it to larger transactions.