How Crucial is it for 6G Networks to be Autonomous?

The sixth generation (6G), unlike any previous generations, is envisioned by 2030 to connect everything. Moreover, in addition to the new use cases 6G is expected to support, it will need to provide a superior performance over 5G. The global connectivity, large-network dimensions, users heterogeneity, extremely-low power consumption, high-throughput, ultra-reliability, efficient-network operation and maintenance, and low-latency requirements to be met by future networks inevitably necessitate the autonomy of 6G. Intelligence, facilitated mainly by the advancement and innovation of the artificial intelligence (AI) technique, is a key to achieve autonomy. In this paper we provide a bird's-eye view of future networks, vision, progress, and objectives. We review some of the 6G technologies that would be mainly enabling the globally-intelligent connected world. We, in addition to discussing the role of AI in future networks, unlike any other review papers provide our original results that emphasize the necessity of deploying AI for 6G networks. We also very importantly identify 6G implementation challenges and key innovative techniques like quantum and blockchain to solve these challenges. This article serves as a starting point for learner to acquire more knowledge about 6G as it combines some of the main contributions in the area and provide some references for getting a more deeper knowledge, and also for researchers to contribute to the field.