Each court system if different and they deal with those who ignore or evade jury duty differently. You might be lucky and they dont follow up, you might get unlucky and be issued a summons to appear in front of a judge to answer why you never showed up for jury duty. You might face a fine ranging from $50 to $1000 and even jail time. Before you make the stupid decision to ignore a jury duty summons, at least look into how the judicial system that called you deals with those who ignore them and make an informed decision.
Has anyone ever heard of a Rav anywhere issuing a psak that one is forbidden to sit on a jury?