In the Internet of Things (IoT) era new connected devices will spread highly sensitive personal data. Sending this type of data to centralized companies represents a serious risk for people’s privacy, since economical or political interests could lead to an illegitimate use of personal information (as shown by Snowden’s revelations). With the purpose of overcoming such status-quo, our research goal is to develop software systems according to the notion of decentralized private-by-design IoT. The basic idea is that data produced by personal IoT devices are safely stored in a distributed system whose design guarantees privacy, leaving to the people -the real data owners- the decision of which of them to share and with whom. To achieve this goal, a possible solution is to leverage the use of Peer-to-Peer storage networks in combination with the blockchain. However, such architecture, despite promising, embeds still limitations, especially in terms of scalability. In this paper we discuss our research motivation, we describe our research idea applied in a possible scenario and we present the scalability problem.