How to derive quantum formalism from first principles?

Suggested a framework to derive the formalism of quantum theory based on the work of Navascues, Pironio and Acin [NJP 10, 073013] (NPA). Specifically, the entries in the Gamma matrices in NPA corrspond to sequential weak values, first analyzed by Mitchison, Popescu and Jozsa [PRA 76, 062105]. However, to obtain the sequential weak values post-selection to the initial state is required, for which we could not find sufficiently strong reason.