The blockchain works great for currency systems, and to an extent, smart contracts (provided they are not needlessly complex, or else you risk losing all stored funds to a bug/hack/unintentional loophole).
This can be summed up by saying that blockchains are only useful for abstract information that benefits from being uncensorable, of which money and contracts are examples. Other examples I would include would be ID systems and data timestamping (Satoshi proved this in an inverted way by adding the famous "The Times 3.1.2009, Chancellor approves 2nd bailout" text to the genesis block,
any data referenced in a blockchain can be verifiably proven to have existed at least after a verifiable time/date).Clickbait for hardcore Bitcoiners:
https://petertodd.org/2016/opentimestamps-announcementhttps://opentimestamps.org/But when the 21m BTC supply was mined, miners will surely shift to a more mining-profitable coin that can lead to a lower Hashing power.
One of the side-effects of the rise of ASICs has been that Bitcoin is sharing its PoW scheme with only a handful of coins, signifcantly reducing the number of possible targets to alternatively point hashing power at. Nonetheless it is of course impossible to predict how the world and cryptocurrencies will look like a 100 years from now, given the latter still exist.
And
this is one facet of a very significant reason to not switch POW algorithms. Thank you.
Don't you mean this is the reason not to be holding any coin using the PoW algo to which Bitcoin's PoW algo is switched?
No. First off, the existing investment in ASIC hardware benefits Bitcoin security insofar as it locks miners into mining Bitcoin (or scamforkshmmm). If Bitcoin miners were forced to dump their existing investments in the trash and restart from scratch, they may very well decide to play the market with altcoinsespecially since they might feel betrayed (and in the case of some of the better miners, they might have a point). Moreover, the existing ASIC base provides a formidable hashpower which could not be rebuilt overnight. Meanwhile, network would be relatively weak. Lesser hashpower equals lesser resistance to anybody obtaining 25%/33%/51% of it.
There is a trade-off involved: Mining is now
much too centralized; and installed base obviously benefits incumbents. But on the other hand, a switch would most benefit whomever could rapidly build out a new installed base. That very well could be the same incumbents.
So as for what I meant. As for what you said:
Any alt already using the hypothetical new Bitcoin POW would be potentially crushed out of existence,
unless the new POW could be
merge-mined. Then, both blockchains would share a mutually beneficial symbiosis; and the existing alt would receive a security boost from the flood of new miners. Of course, I dont see great prospects for this unless the coins are not economic competitors; observe that Namecoin, inventor of merged mining, does not compete with Bitcoin as a currency.