The consequences would be the same for not fulfilling any obligatory ibadah i.e. missing farz Salah, not giving zakat due and the same goes for not completing farz fasts. The exact quantification of such consequences cannot be done as ibadah is a matter between God and the person, so ultimately it is Allah who will decide the nature and quantification of such consequences. But the consequences can be grave, so we Muslims should be mindful of that.