This project, and the original phonebloks project, received a lot of (totally legitimate) criticism on reddit. The original stick-the-blocks-anywhere design was technologically impossible, which it why it was nixed. This design is feasible, but you're going to have to accept huge tradeoffs for modularity. This phone, if produced, will be much thicker, heavier, more expensive, and have significantly shorter battery life and less durability than a contemporary unibody phone. It looks great in a render, but when folks see what they have to give up for the wow-factor of a legophone, I doubt many will actually buy one.
A more practical design would be more closely related to desktop PCs - standardized modules with standardized connectors inside a case with standardized mount points. The case/display/mainboard would have to be a single component, but the SoC, storage, camera, radio, & battery could all be swapped around with basic hand tools.