We cannot say this as of yet. Bitcoin has been the biggest coin that supports pow so till bitcoin is living on pow algorithm i do not think that pow is going anywhere yes some coins are changing to pos algo but it will not put much effect on pow untill we have bitcoin with pow protocol.
That's certainly true, mate. If Bitcoin remains as a PoW cryptocurrency, then the algorithm itself may never die. I believe that Bitcoin has stayed with PoW, simply because it's the most secure consensus algorithm to date. While there's a huge flaw inherent within PoW which makes the formation of centralized mining pools possible, it could easily be fixed with the newly proposed Optical PoW (PoW+) or a change in the stratum protocol (I believe it's called betterhash).
Despite this, PoS is still the most energy efficient consensus algorithm to date. The benefits are numerous not only limited to energy efficiency, but also faster speeds and low fees. Because of this, Ethereum will switch to PoS soon making the platform scalable than ever. With Ethereum's current prices and the minimum amount of coins required for staking, it'll become extremely expensive to perform a 51% attack on its blockchain.
Nonetheless, time will tell us whenever PoS would fail or live alongside PoW and other consensus algorithms for a long time. Just my opinion
It's a welcome idea and I see it succeeding. There have been several attacks and hacks on ethereum platform. If the mechanism of POS will make it tougher of any for of attack to be executed, then it will be of great help, most especially for tokens that use the platform of ethereum. POW is in its simplicity, which is why Isis very vulnerable, while POS is more complex, by encoding extra rules into its software.
PoW is terrible for small blockchain networks, as the hacker could easily perform double spending at a low cost. On the other hand, PoS seems to be much more expensive than PoW since it relies on a minimum ownership of coins based on their current price. The only downside of this is that if a specific cryptocurrency is dirt cheap, then double spending attacks would become inexpensive to perform. Which is why, I believe that the best solution would be a hybrid PoW/PoS model. This takes advantage of the security of the PoW consensus algorithm, while adding an extra level of security and energy efficiency by staking.
Speaking of hybrid consensus, Magi (XMG) is a hybrid cryptocurrency which provides the benefits of both PoW and PoS, making double spending attacks extremely expensive to perform by a hacker. On the other hand, dPoW (Delayed Proof of Work) is a different consensus algorithm that provides a high level of security to any blockchain network, because it "notarizes" transaction data into the Bitcoin blockchain. Since Bitcoin is extremely secure, cryptocurrencies which make use of dPoW would obtain the same level of security as Bitcoin making double spending attacks unfeasible.