I think there is an inherent problem with all of the current mining, yes they create an incentive for people to run the network but they are becoming an outdated model and largely centralised which defeats the purpose of most cryptocurrencies.
PoW
As we know, Proof-of-Work is ridiculously energy intensive, to the degree that it will soon (couple of years) become unsustainable. If you look at the energy consumption of Bitcoin (simply the most well established and therefore easy to find data on):
While Bitcoin was consuming about 14 TWh / year in July 2017, this has increased to 44 TWh / year by January 2018 or triple its consumption. In terms of energy consumption, this comes down to about 385 KWh consumed per actual transaction, which means you could power approximately 13 households in the US for one day for each transaction processed by the Bitcoin network.
Bitcoin has a daily consumption of 119,831,467 (20/01/2018) which could power a total of 4,049,860 households daily (at a consumption rate of 29.5890 KWh). I.e. Bitcoin consumes as much power as a country with a population of 4 million people, itcurrently consumes more energy than the Republic of Ireland, or New Zealand or Hungary and is just trailing behind Peru on a global scale.
All this for a slow transaction system.
PoS
While a better approach and certainly a more environmentally friendly approach, there are still some potential inherent problems with this system; those with a higher stake (I.e. coins in possession by the node) will still have the ability to control the network (much liker miners in PoW) and the current miners are the ones controlling a large percentage of the coins (theoretically, they could simple HODL everything they mine) and as such this model also leaves itself open to centralisation.
The owners / founders of the coin can circumvent this by keeping a large enough amount of coins out of circulation and into their control but this again is centralisation.
PoC
While this will initially create a more level playing field, provided this is successful as a mining approach, I would predict that this would travel down a very similar path to PoW and PoS where a small group of people control a rather large piece of the network.
If you are a current Bitcoin miner and you see PoC and coins with PoC take off, it would be relatively cheap for you to start adding different hardware to your mining pool, purely focused on PoC and you will get rigs with as many high capacity hard drives as possible to give you greater mining chances; gradually surpassing the network at large.
Granted this may take a bit longer (since everyone has some spare space on their HD) but as soon as you start putting in a battery of the Samsung 15.36TB SSD (USD 10,000) and solely dedicate this rig to mining or better yet a battery of the to-be-released Seagateâs 60TB SSD which again can be fully delegated to mining; you can see a shift in power happening quite fast.
Iâm not saying BurstCoin is a bad idea, at all, Iâm all in favour of decentralisation, but I personally believe that any model that requires some sort of Proof-of-⌠before transactions are bundled and added into blocks and those blocks are mined, will always ultimately become more centralised.
Time will tell if this model will fare better than PoW / PoS.
If you look at how Tangle, Raiblocks and Hashgraph mine, you will see a far more decentralised and fair system; which is what cryptocurrencies were meant to be; that, I believe is the direction that will be sustainable for the future.
Just my two cents obviously