Well, that's not a manifested article, but simple a research question. We need more and better material of the 20ies of 15th century in Italy to understand the Michelino deck in its context.
Some aspects: What influence did the council of Constance take on the mood of the time in Italy? Were more wealth in North Italy in the 20ies than in the 30ies? How did the stabilisation of the Milanese dukedom influence the situation? What about Greek gods generally? Are they really already a manifested theme in art or is the Michelino deck a revolutionary change in direction "renaissance"? Is it correct to see the action's of San Bernardino as part of a conservative movement? And other questions.