Lack of interoperability
Current blockchain technologies do not easily interoperate. While it is possible to write an application that can communicate with multiple blockchains, those blockchains do not have the natural capability to communicate with each other. In many cases, the fundamental approach to transactions and governance may not be compatible. For instance, in the Ethereum network, any user can send any token to any other user, no permission required by the recipient. The recipient is free to ignore the new tokens if they wish, but they still have them (which results in some interesting tax questions). In the Stellar network, however, a user must issue a trustline to another in order to receive custom tokens issued by that user.
Similarly, many networks offer multisignature and multiuser wallets on-chain. However, without a centralized application sitting outside the blockchains themselves, there is no way for users to easily manage all of these networks in one place. This is part...
