Surefire modularity is a mix of the technology used, cost saving design choices, and large volume of production with limited competition leading to popular aftermarket support for improved parts and squishing new tech in old platforms,
A new modular platform would need to be a sort of agreed community standard design, preferably designed with the thermal needs of LEDs taken into account. The closest thing in the custom scene is the proliferation of Mac derivative designs but interoperability is somewhat limited by everyone making small tweaks and optimizations for their application