Decentralized physical infrastructure network (DePIN) is an emerging research topic in Web3 and blockchain. By combining blockchain, IoT and tokenomics, DePINs are expected to disrupt existing IoT business models and enable Web3 communities to build innovative, machine-driven and decentralized IoT networks and applications. Due to the characteristics of DePINs such as the large number of smart devices and network scale as well as the interactions with blockchain, scalability remains to be one of the key challenges. In this position paper, we outline the core ideas and components for building a rollup-centric scalable architecture for DePINs. The proposed architecture takes a modular design approach and leverages off-chain computing and zero-knowledge proofs to address the scalability challenge. This work is expected to highlight the importance of this new research direction and shed some light on potential solutions.