Bitcoin is the first cryptocurrency ever made and the first fork of a cryptocurrency protocol. It was the first to introduce the concept of encryption and decentralization of money. Since it was created in 2009, the protocol is now getting obsolete. The fact that about 150'000 transactions are unconfirmed is the evidence. Bitcoin cannot handle an high traffic of users, because most of the people are starting to have transactions not mined (and stuck) for days or weeks. If PoW already showed its negatives with the high energy cost, now the evidence arrives from the quality of service, when the traffic involves more people and the fees attached to transactions increase to get higher priority.
If the traffic would increase even more, with the current level of difficulty the entire system is doomed to burst. There are other cryptocurrecies that solve most of these problems. Bitcoin is now stronger than other cryptocurrencies because it was the first and it has a larger market capital and a larger user base. However, it doesn't mean that its concept is better and that it will survive in the future. In my opinion, Bitcoin will burst when the system will not be able to handle all the transactions. We can see the first symptoms right away. Check this website:
You can see with your eyes that the number of unconfirmed transactions is very high in this moment, and it will increase in the future with the increment of people making transactions. Most of the transactions are not mined because their fees are too low for the miners that are wasting computational power to get the best profit at the least expense. They wasted millions of dollars to create mining farms with powerful ASICs and graphics cards. They want to mine transactions with the higher fees to have a payback and make even more money. As nobody is interested in wasting an outstanding amount of power to mine transations that have lower fees than others, the transactions with lower fees are rejected until they will be eliminated and created again with higher fees, in an infinite loop of speculation that is creating a Transaction Fee Bubble. As you can see from the above chart, the transation fee average incremented from $0.27 to $27, 100 times in just one year. The fees are growing so fast that transactions will be not convenient anymore. People will migrate their money to less expensive currencies, where transactions will not get unconfirmed so easily. For instance, I'm started to do it right now because I had unconfirmed transactions and no decent way to accelerate them without paying mining pools or other fees. And If I'm doing it, I'm sure that in this moment there are other people that are making the same consideration. So, this is the reason why I believe that Bitcoin is doomed to burst in the future.