nothing happens
you don’t receive the graces of participation at Mass and reception of communion.
If you deliberately miss Mass because you decided to deliberately flout the 3rd commandment and the law of the Church, you have also committed a mortal sin. If you cannot get to Mass because of legitimate reason–there is no Catholic Mass where you are, illness, caring for an infant or sick person, urgent demand of charity, necessary work, then you have no obligation so the matter does not arise.