The main conflict in the future besides quantum computing, and because of quantum computing, is the decision between transparency and privacy while also deciding on security or speed of blockchains (Drescher 2017). There is a need in the very beginning to decide on these factors when building a new blockchain system.
Technically, transparency is a question to whom you give the reading rights in a blockchain. If all have the reading rights, as in Bitcoin with its ledger, then system is transparent, if not, then it is more private. In addition, speed can be found out by the amount of writing rights in the blockchain. The less peers have the right to write information to the blockchain ledger, the more secure the system becomes.
While current blockchains like Bitcoin consider transparency more important than privacy and speed more important than security, this might change in the future. Transparency enables many users and a public ledger to be distributed to all peers, while privacy protects the distribution of the ledger, making the system design centralized (see Chapter 1). Speed enables many more transactions in a given time frame while security of these transactions can be compromised by i.e. quantum computing.
It is to be expected that these decisions between main operational factors of any blockchain will be more varied in the future. There will be both blockchains that concentrate on the privacy and security as well as those which choose transparency and speed. Most probably banking and logistics will value the former while tourism and small-scale businesses the latter. It is worth noting that Bitcoin is about transparency and speed, which might entail changes in its system architecture in the coming years. It is also worth to note that peer-to-peer architecture of blockchains may well be a passing phase with more centralized designs in the future.
It can also be argued that transparency and security do not need to be in direct conflict when designing a blockchain. In the future, the blockchains can also be combined to withhold common, private, and secure blockchains together. There can be i.e., a global common blockchain layer, on top of which more spesialised blockchain functions are built upon. Transactions can take place in high quantities in secure blockchains, from which only the end results are given to the common layer of the blockchain. This enables different functionalities on, say, Ethereum, which can then withhold the common data for multiple blockchains.
It should also be noted that as much of the data is dispersed in varies data storages, such as cloud services, blockchain may be intensively used to keep this sort of data secure. Centralized design here does not affect the end result so much, as the data is being monitored anyway by a centralized authority, as in the case of corporations making sure their data is the same as before. It might be that in the future data is handled over a centralized blockchain technologies. There are other possible technical innovations, which use centralized design of blockchain to generate value, as for example distributed computing.
As prediction is hard, especially concerning the future, we leave the technical discussion about the future of blockchain with the note that with the advancements in computing power, more centralized, private and secure blockchains will be used until quantum computing is more evenly dispersed on the Internet. However, not all blockchains need to be as secure as others and therefore systems that are prevalent currently, favoring transparency and speed will also be used in the future in less-critical instances.