The Inteet of Things (IoT) has been evolving for more than a decade.Technological advancements have increased its popularity, but conces and risks related to IoT are growing considerably along with the increased number of connected devices.In 2013, a new cryptography-based infrastructure called blockchain emerged with the potential to replace the existing cloud-based infrastructure of IoT through decentralization.In this article, we provide a taxonomy of the challenges in the current IoT infra-structure, and a literature survey with a taxonomy of the issues to expect in the future of the IoT after adopting blockchain as an infrastructure.The two architectures are compared based on their strengths and weaknesses.Then a brief survey of ongoing key research activities in blockchain is presented, which will have considerable impact on overcoming the challenges encountered in the applicability of blockchain in IoT.Finally, considering the challenges and issues in both infrastructures and the latest research activities, we propose a high-level hybrid IoT approach that uses the cloud, edge/fog, and blockchain together to avoid the limi-tations of each infrastructure.