A complex crowd-sourcing problem such as open source software development has multiple sub-tasks, dependencies among the sub-tasks and requires multiple workers working on these sub-tasks to coordinate their work. Current solutions of this problem employ a centralized coordinator. Such a coordinator decides on the sub-task execution sequence and as a centralized coordinator faces problems related to cost, fairness and security. In this paper, we present a futuristic model of crowd-sourcing for complex tasks to mitigate the above problems. We replace the centralized coordinator by a blockchain and automate the decision-making process of the coordinator. We show that the proposed solution is secure, efficient and the computational overhead due to employing a blockchain is low.